Pour les posters : PAMO et Matière condensée Congrès général SFP 2017 Développement des photodétecteurs à puits quantiques accordables dans

la gamme du THz

C. Abadie1, B. Paulillo1, S. Pirotta1, L. Li2, E.H. Linfield2, R. Colombelli1

1 Centre de Nanosciences et de Nanotechnologies, CNRS, Univ. Paris-Sud, Université Paris-Saclay,

C2N – Orsay, 91405 Orsay cedex, France 2 University of Leeds, School of Electronic and Electrical Engineering, University of Leeds United Kingdom

La gamme spectrale du térahertz (0.3-30 THz) comporte un enjeu fondamental dans les applications médicales en raison des raies d’absorption des molécules organiques dans cette gamme, ou même – en perspective – dans les télécommunications.

Les détecteurs présents sur le commerce sont pour la plupart des dispositifs thermiques qui ont une sensibilité assez faible ou bien ne sont pas rapides. Les dispositifs photodétecteurs à puits quantiques (QWIP) sont beaucoup plus sensibles, mais nécessitent des températures cryogéniques de fonctionnement.

Mon objectif est de développer des QWIP accordables en fréquence de détection, et aussi rapides, à base de GaAs/AlGaAs. Ils fonctionneront à une fréquence centrale de résonance autour de 3 THz en utilisant une géométrie inspirée des résonateurs "split ring" en 3D. Notre équipe a déjà démontré que cette géométrie [Fig. 1a] permet d’accorder1 la fréquence de réponse entre 1-3 THz en changeant l’antenne (partie inductive du micro-résonateur RLC1). Pour construire des dispositifs actifs (détecteurs et lasers), nous devons résoudre le problème du court-circuit intrinsèque dans cette géométrie. Une solution2, apportée par notre équipe [Fig.1b] consiste à graver l’or du plan de sol pour obliger le courant à passer par la région active plutôt que par l’antenne conductrice.

Une approche alternative présentée dans ce résumé est le dépôt d’une couche isolante de Si3N4 de 300 nm pour séparer le contact du haut et celui du bas. Avec des simulations numériques par éléments finis, nous avons modélisé le comportement électromagnétique de la structure. Les premiers dispositifs fabriqués [Fig.1c] sont caractérisés électriquement à température ambiante. Les dispositifs uniques ont une résistance de 1-10 MΩ alors que les réseaux de dispositifs 5x5 ont des résistances typiques de l’ordre de 100 kΩ. Des tests sont en cours avec une couche de Si3N4 déposée par pulvérisation plutôt que par PECVD pour améliorer la robustesse mécanique du dispositif.

Figure 1 : .(a) (b) (c) Trois images MEB des réalisations successives de la géométrie 3D SRR

1. B. Paulillo et al. (2014), Optics Express, Vol. 22 (18), pp. 21302-21312 2. B. Paulillo et al. (2016) “Terahertz meta-atom quantum well photodetectors” Lasers and Electro-Optics (CLEO), USA 2016.

Congrès général SFP 2017 Division Matiere Condensé

Towards electron spin hyperpolarization via radiative cooling

Bartolo Albanese1, Sebastian Probst1, Denis Vion1, Daniel Esteve1, Klaus Moelmer2, John J. L. Morton3, and Patrice Bertet1

1 Quantronics group, CEA Saclay, France 2 Department of Physics and Astronomy, Aarhus University, Denmark 3 London Centre for Nanotechnology, University College London, United Kingdom

Electron spin resonance (ESR) spectroscopy is widely employed for the detection and characterization of paramagnetic species and their magnetic and chemical environment 1. In ESR the spins precessing around an applied static magnetic field are first excited by microwaves and subsequently emit a signal into an inductively coupled resonant cavity. A high degree of polarization is essential to maximize the signal. Here, we are interested in increasing the polarization beyond thermal equilibrium. In the present work we propose a new universal hyperpolarization scheme based on the coupling of the spins to a colder electromagnetic bath via Purcell-enhanced radiative relaxation.

For spins in solids, radiative relaxation is completely negligible. The dominant process is relaxation to phonons. However, by coupling the ensemble to a high Q resonant cavity with a small mode volume, the spontaneous emission rate can be enhanced up to the point where the radiative relaxation dominates. This enhancement is called Purcell effect 2. The goal of our experiment is to demonstrate Purcell enhanced thermalization of a spin ensemble to a colder radiation bath while the crystal lattice remains at higher temperature.

The spin system under study is an ensemble of bismuth donors implanted into a host silicon crystal. The spins are inductively coupled to a high Q superconducting niobium resonator. The silicon crystal is installed at the 1 K stage of a dilution cryostat while the resonator is coupled to a 10 mK black body. In this configuration, the electronic spins thermalize to 10 mK via radiative relaxation while the silicon crystal remains at 1 K. We expect an increase of the ESR signal by a factor 5 compared to the case without hyperpolarization. 1 A. Schweiger and G. Jeschke, Principles of Pulse Electron Magnetic Resonance (Oxford University Press, 2001) 2 Purcell. E.m spontaneous emission probabilities at radio frequencies. Phys. Rev. 69 ,681 (1946)

1

The Si:Bi spin ensemble is placed into a high Q overcoupled cavity at 1 K which is connected to a cold bath at 10 mK. An external magnetic field tunes the spins into resonance with that cavity. The spins will then thermalize to the 10 mK bath.

Congrès général SFP 2017 Division Matière Condensée

LES PREMIERS PRINCIPES DE CALCULS DES PROPRIETES

ELECTRONIQUES ET THERMIQUES DES FLUOROPEROVSKITES

BaLiF3 ET SrLiF3.

S. Amara Korba , N. Chouit, S. Benlamari, H. Meradji et S. Ghemid

Laboratoire LPR, Département de Physique, Faculté des Sciences, Université de Badji Mokhtar Annaba.

Dans ce travail nous présentons les premiers principes de calculs des propriétés électroniques et thermiques des composé BaLiF3 et SrLiF3 qui sont deux fluorures à structure pérovskite.

Nous avons utilisé dans nos calculs la méthode des ondes planes augmentées et linéarisées FP-LAPW implémentée dans le code wien2k [1]. Pour déterminer le potentiel d’échange et de corrélation nous avons utilisé l’approximation de la densité locale (LDA) et l’approximation du gradient généralisé (GGA).

Les composés BaLiF3 et SrLiF3 présentent un gap énergétique direct dans la direction et pour déterminer ce gap, nous avons employé l’approximation MBJ qui a donné des valeurs assez proches des valeurs expérimentales [2].

Pour déterminer les propriétés thermiques nous avons employé le modèle quasi harmonique de

Debye dans un intervalle de température et de pression allant de 0 à 600 K et de 0 à 12 GPa

respectivement. Nous avons étudié l’effet de la température et de la pression sur le paramètre du

réseau, le module de compressibilité, la capacité calorifique CV et CP, la dilatation thermique et la

température de Debye.

1. P. Hohenberg, W. Kohn, Phys. Rev. B 136, 864 (1964) 2. 2. T. Nishimatsu, N. Terakubo, H. Mizuseki, Y. Kawazoe, DA. Pawlak, K. Shimamuri and T. Fukuda, Jpn. J. Appl. Phys. 41,

365 (2002)

1

Congrès général SFP 2017

Room Temperature High Performances Quantum Cascade Detectors

Z. Asghari1, A. Mottaghizadeh1, D. Palaferri1, D. Gacemi1, M. Amanti1, A. Vasanelli1, Y. Todorov1, A. Evirgen2, A. Delga2, C. Sirtori1

1 Université Paris Diderot, Laboratoire Matériaux et Phénomènes Quantiques, 75013 Paris, France 2 III V Lab., 91767 Palaiseau, France

Mid-infrared (MIR) detection has wide range of applications in spectroscopy and has recently

shown strong potential in the field of optical communications. Mercury Cadmium Telluride (MCT) detectors are widely used for application in the MIR [1]. They have a high sensitivity (~1010 cm. Hz1/2 /W) but they have a modulation bandwidth limited to less than 1 GHz. On the contrary devices based on intersubband transitions have demonstrated high frequency bandpass in excess of 100 GHz [2]. There are two types of intersubband detectors: quantum well infrared photodetectors (QWIP) and quantum cascade detectors (QCDs). QCDs operate in photovoltaic mode and have the advantage, over the QWIPs, to operate at room temperature, with fairly high photoresponsivity [3].

The working principle of QCDs is based on a vertical intersubband transition followed by an extractor made of a ladder of electronic states in a cascade shape. Their specific design enables detection at zero bias with minimal dark current with detectivity limited by the thermal noise at room temperature [4].

The QCD of our investigation is based on GaInAs/AlInAs quantum wells designed and grown at III-V Lab and was processed into mesa devices of 200–100µm in diameter. The detection

wavelength is 4.9µm. In Fig. 1a we present the photocurrent spectra as function of the temperature taken from 78K to room temperature. In the inset of Fig.1a we report background current measurement for the same device: values as low as (~10-10A) are reached at cryogenic temperature.

The detectivity at 0 bias has been measured as a function of the temperature (Fig. 1b). The

detectivity shows a typical background limited infrared performance (BLIP) with a constant value below a certain temperature, TBLIP. For our devices TBLIP is met at 142K with a detectivity of D*BLIP = 1.3x1011 cm. Hz1/2 /W. The next goal of our investigation will be to use the QCDs in a microwave packaging to fully exploit the very wideband of these device. Ultimately, they will be used as receivers in a free space optical communication link at around 5µm.

1. J. B. Varesi, “Fabrication of high-performance large-format MWIR focal plane arrays from MBE-grown HgCdTe on 4 ̋silicon substrates„ J. Electron. Mater. 30(6), 566–573 (2001). 2. H. C. Liu, Jianmeng Li, E. R. Brown, K. A. McIntosh, K. B. Nichols, and M. J. Manfra “Quantum well intersubband heterodyne infrared detection up to 82 GHz„ App.Phy.Lett. 67 (11) (1995) 3. H. Schneider and H.C. Liu, Quantum well infrared photodetectors. Springer (2006) 4. D. Hofstetter, F. R. Giorgetta, E. Baumann, Q. Yang, C. Manz, K. Köhler “Mid-infrared quantum cascade detectors for applications in spectroscopy and pyrometry” Appl Phys B (2010) 100: 313–320

Fig. 1a: Normalized photocurrent spectra at different temperatures. Inset : Current-Voltage curves at background conditions. Fig. 1b:

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O1 Congrès général SFP 2017

Effect of Ar dilution of the reactant gases in Microcrystalline silicon prepared by PECVD for photovoltaic solar energy conversion

H. Ayed1,2, N.Benslim2, L.Béchiri2, M.Benabdslem2,L. Mahdjoubi2 and

T.Mohammed-Brahim3

1Université el arbi Tébessa Tébessa,12000, Algérie.

2 (LESIMS) Laboratoire, Université Badji Mokhtar BP.12 Annaba, 23000, Algérie.

3GM-IETR, Université RENNES I, 35042 Rennes Cedex, France.

Microcrystalline silicon (c-Si) is widely studied and applied in many fields where the technology devices needs crucially low substrate temperatures. The most commonly example is the flat panel displays that use polysilicon thin film transistors TFT, made directly on glass substrates. In another side, many works on photovoltaic solar cells have been devoted to this material.

Plasma enhanced chemical vapour deposition (PECVD) is a very promising method for industrial scale fabrication of microcrystalline silicon solar cells since the technique is well applicable for large areas, and high deposition rates can be obtained. We have investigated the effect of Ar dilution on the growth process and the material properties of microcrystalline silicon. The major benefit of Ar addition in the PECVD process, using H2 and SiH4 as reactant gases, is an improved stabilization of the plasma. However in our case the noble gas Ar is used in order to improve the net work structure by promoting growth at the initial stage of the deposition process reducing the amorphous interfacial layer and leading more rapidly to the columnar aggregation.

In this paper, study of (c-Si) thin films is presented and an attempt to correlate the effect of Ar dilution with optical gap and activation energy of the film conductivity is undertaken.

1.O. Dulieu and S. Willitsch,Cristaux coulombiensDe la technologie quantiqueà la chimie proche du zéro absolu,Reflets de la Physique44-45, p 91(2015)

1

Electrical conductivity of materials based on DC and High-

frequency technique

M. Benabdeslem1, N. Benslim1, L. Bechiri1, A. Djekoun1, S. Rahal1, J. G. Theobald2 and M. Fromm2

1Laboratoire des surfaces et interfaces (LESIMS). Université d’Annaba (Algérie).

2 Centre de Microanalyse Nucléaire, UFR Science & Techniques, 16 route de Gray, 25030,

Besançon (France)

In general, conductivity measurements on materials can be strongly affected by the nature of

the electrical contacts, due to the resistivity. In this work, we describe a new contactless

technique based on high frequency electrical measurements. Resonant methods at 9192

MHz were carried out in a rectangular resonance cavity. The conductivity σHF was deduced

from the variation of the quality factor and from the frequency shift. The potential of this

contactless high frequency measurement technique was applied for bulk crystals of CuInSe2

(CIS) grown by vacuum fusion technique with specific proportions of Cu, In and Se. The

measured high frequency conductivity σHF was then compared with σDC measured from

conventional DC (direct current) technique. Conductivity values obtained varying in the range

[3.10-3-7.10-3] -1cm-1 didn’t show significant discrepancies between the two techniques.

1. F. Torrealba-Anzola, A. Chambaudet, J.G. Théobald, M. Jouffroy, C. Jany, F. Foulon, P. Bergonzo, A. Gicquel, A. Tardieu, Diamond Relat. Mater. 7 (1998) 1338. 2. M. Jouffroy, A. Gire, J.G. Théobald, G. Bardèche, F. Torrealba-Anzola, A. Chambaudet, J. Phys. Chem. Solids 60 (1999) 181. 3. A. Gire, M. Jouffroy, J.G. Théobald, O. Bonhké, G. Frand, Ph. Lacorre, J. Phys. Chem. Solids 58 (1997) 577.

Figure 1:. Conductivity versus Cu/In in DC and high-frequency regimes.

First-principles study of structural, electronic and optical properties of

MgSiSb2

S. Benlamari, H. Meradji and S. Ghemid Laboratoire LPR, Département de Physique, Faculté des Sciences, Université Badji Mokhtar, Annaba, Algeria.

In this work, we report the results of

structural, electronic and optical properties of the ternary II-IV-V2 (MgSiSb2) chalcopyrite semiconductors using the Full-potential linearized augmented plane wave (FP-LAPW) scheme in the frame of generalized gradient approximation (GGA). The optimized equilibrium structural parameters (a, c and u) are in good agreement with theoretical results. Band structure and density of states show that

MgSiSb2 has a direct gap (-) of about 0.80 eV. To understand the optical properties dielectric function, refractive index, and extinction coefficient are calculated. This compounds present very week birefringence.

To our knowledge, most of the studied properties of this compound are reported for the first time and still awaits experimental confirmations.

1

Experimental and DFT investigations of Kesterite Cu2ZnSnS4

compound for solar cell applications

N. Benslima, M. Chaouche

a,, K. Hamdani

a, M. Benabdeslem

a, L. Bechiri

a, M. Boujnah

b,

A. Benyoussefb ,

a LESIMS, Département de Physique, Faculté des Sciences, Université Badji

Mokhtar- Annaba, BP. 12, 23200 Sidi Amar, Algeria bLaboratoire de Magnétisme et Physique des Hautes Energies BP 1014, Faculté des

Science, Mohammed V- Université, Rabat, Morroco

*E-mail: bechiri@hotmail.com

Abstract

The quaternary compound semiconductor Cu2ZnSnS4 (CZTS) of the I2-II-IV-VI4 family is

a new type and an excellent candidate to replace the absorbers current used in thin film solar

cells. CZTS offers favorable (suitable) optoelectronic properties that are advantageous for thin

film applications and contains abundant elements. CZTS thin films were prepared by thermal

evaporation from Cu2SnS3 and ZnS initially mixed by mechanical alloying process. Structural

and optical properties of CZTS films have been studied. X ray diffraction results showed that

the semiconductor has the Kesterite structure, the optical absorption coefficient and band gap

energy of the thin films were about 10 4 cm−

1 and 1 .45 eV respectively. The structural and

optical properties of Kesterite CZTS, studied by using the full potential linearized augmented

plane wave method (FP−LAPW) within the density functional theory (DFT). The optimized

lattice constants by LDA-mBJ for the CZTS compounds are listed as follows: a = 5,367 Å,

c = 10.744 Å and showed good agreement with our experimental results.

Bi-stabilité et hystérésis dans les écoulements granulaire

Philippe Boltenhagen, Alexandre Valance, Renaud Delannay & Joris Heyman

Institut de Physique de Rennes, UMR 6251

Bat 11A, Pièce 131, Campus Beaulieu

Université de Rennes 1

35 042 Rennes Cedex, France

De nombreux écoulements granulaires, que ce soit dans la nature ou en situation

industrielle, relèvent du type ‘écoulements gravitaires sur plan inclinés’. Ces écoulements sont

généralement confinés par des bords latéraux. La plupart des études expérimentales réalisées

portent sur des inclinaisons assez faibles pour lesquelles sont obtenus des écoulements stationnaires

(invariants en temps) et établis (invariants le long de l’écoulement) de propriétés homogènes

(fraction volumique uniforme, écoulement cisaillé sur toute l’épaisseur).

Nous montrons ici, que pour une inclinaison et un débit massique imposés, il est possible

d’observer non seulement le régime habituel stationnaire établi, mais également un autre régime

non établi.

Cette transition est réversible, et est induite par une instabilité externe.

Nous montrons les profils de vitesse mesurés pour différentes positions le long de la plaque

de métal et pour les deux types de phases observées.

C’est une première fois qu’une telle transition de phase dans un écoulement confiné est

observée. Nous caractérisons l’ensemble des phases et traçons un diagramme des phases.

O1 Congrès général SFP 2017

Microstructure and magnetic properties of nanostructured NiS2

powders prepared by high energy mechanical milling

N. Boudinar1,#, A. Djekoun1, A. Otmani1, B. Bouzabata1, J. M. Greneche2

1Laboratoire de Magnétisme et de Spectroscopie des Solides, Université Badji Mokhtar, Faculté des sciences B. P: 12 (23000) Annaba –Algérie # Ecole Supérieure des Technologies Industrielles - Annaba, Algérie.

2Laboratoire de Physique de l’Etat Condensé, UMR CNRS 6087 Université du Maine, Faculté des Sciences 72085 LEMANS Cedex 9 –France

Various techniques for the preparation of ultra-fine powders have been developed such as spray pyrolysis, mechanical milling and physical vapor deposition (PVD). Among them, mechanical alloying (MA) has attracted a lot of attention in recent years because it has proved to be an ideal tool for the generation of a wide range of systems, including dispersion-strengthened materials, supersaturated solid solutions, intermetallics and nanocrystalline materials.

In this investigation, nanocrystalline NiS2 alloy has been synthesized from the elemental powders by mechanical alloying (MA). Microstructural evolution and magnetic properties of the mechanically alloyed powders at different milling times have been examined by a combination of X-ray diffraction (XRD) and vibrating sample magnetometer (VSM).

The analysis of X-ray diffraction (XRD) patterns indicates single phase. The parameter such as lattice constants (a) and crystallite size (D) were calculated from XRD data. The crystallite size is found in the ordre of 20 nm. The magnetic properties such as saturation magnetization (Ms), coercivity (Hc), remanence (Mr) and squareness ratio (Mr/Ms) were calculated from hysteresis loops. The coercivity increases from 30 Oe to 110,4 Oe while the saturation magnetization decreases from 176.6 to 120.3 emu/g as function of milling times.

Keywords: Nanostructure; Ball milling technique; Structural properties, Hysteresis loops; Magnetic properties.

Division MatièreCondensée (DMC) Congrès général SFP 2017

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Study of the resistance to crack propagation inthermal insulationmaterials

SeddikBOURAS,FaridGHELDANE

Laboratory of Advanced Materials,University of Annaba, B.P. 12, 23000 Annaba, Algeria Corresponding author:bourasseddik@gmail.com

Abstract: Alumina presents a crack growth resistance that translates stable crack propagation

before the fracture. In this case, the material toughness is not constant but increases with the

crack extension. It depends on the crack extension a from an initial crack size a. This study

was carried out by hertzian indentation and acoustic emission. Thehertzian indentation consists

to load specimen surface using a spherical indenter. Critical load Pc is determined by the

highest acoustic emission peak. The loads below Pc provoke weak acoustic emissions

translating a sub-critical crack propagation correlated to the resistance to crack

propagation.Such materials can be used for the economy of energy in many areas for their

thermal and electrical isolation character. Keywords:, R-curve, Resistance to Crack Propagation, Hertzian Indentation, Acoustic Emission.

Results

In hertzian indentation tests, the used monotonous loading leads to the progressivelygrowth of

circular cracks until the formation of a complete circle. Figure1 shows the result of loading

followed by an unloading, and the recordedacoustic emission. The complete circle occurred at

the fracture critical load Pc = 900 Nidentified by the peak of the highest amplitude. The loads

below Pc provoke weak acoustic emissions translating a sub-critical crack propagation

correlatedto the resistance to crack propagation.Figure 2 shows that the arks numbering rate

decreases first. That means that every time interval contains less acoustic events than the

previous interval and it translates a resistance to cracks propagation. Close to the critical load,

very fast growth of the arks numbering rate is obtained.

Figure 1 Acoustic emission and loading. Figure 2 Arks numbering rate.

Matière condensée Congrès général SFP 2017 Magnétisme frustré

Mesures de bruit magnétique à très basse température

Cathelin V.1, Lhotel E.1, Paulsen C.1

1 Institut Néel, CNRS, 38000 Grenoble, France

Dans la dernière décennie, les matériauxmagnétiques nommés "glaces de spins" (deformule R2Ti2O7 où R correspond à Dy ou à Ho)ont été au centre de l 'attention de lacommunauté des chercheurs en magnétisme.En effet, il a été montré que les excitationsmagnétiques dans ces systèmes sont desquasiparticules magnétiques émergentesportant une charge isolée, identifiées commedes monopoles magnétiques.

Figure: Réseau pyrochlore

Jusqu'à présent, seules des mesures indirectes ont permis de mettre en évidence un courant demonopoles dans les glaces de spins. Ma thèse a pour but de détecter directement les "monopolesmagnétiques" et leurs fluctuations grâce à des mesures de bruit magnétique. Le principe reposedonc sur la détermination expérimentale des déviations à la relation de fluctuation-dissipationdans les glaces de spins, afin de caractériser quantitativement l'état hors-équilibre et ladynamique des monopoles à très basse température. Cela implique le développement d'unenouvelle et unique expérience, permettant la mesure de fluctuations magnétiques jusqu'à de trèsbasses températures grâce à un magnétomètre à SQUID situé à l'intérieur d'un réfrigérateur àdilution 3He-4He. Je présenterai les concepts physiques liés à cette étude (susceptibilité et bruitmagnétiques, physique des glaces de spins, détection à SQUID) ainsi que les principalesdifficultés soulevées (perturbations mécaniques et magnétiques, maintien d'une sensibilitésuffisante en présence de champ magnétique d'excitation).

1

O1 Congrès général SFP 2017

Effects of Fe additions on HPHT synthesis methods characteristics of

novel particle reinforced metal-matrix compositesin theTiO2–Al–C system

N. Chakri1, A. Benaldjia1 2, B. Bendjemil1, 2,3 , B.Itaalit3 , M. Moyane3 , D. Vrel4

1LASEA, Dept of Chemistry, University of Badji-Mokhtar, 23000 Annaba, Algeria 2DGM, University of 8 Mai 1945 Guelma, 24000 Guelma, Algeria 3LUSAC, EA 4253, 60 rue Max Pol Fouchet, CS 20082, Université de Caen Basse-Normandie (UCBN), 50130 Cherbourg-Octeville, France. 4LSPM, Avenue Jean-Baptiste Clément, CNRS-UPR 3407-Université Paris 13, France. chakrine@yahoo.com

The aim of the present study was to investigate the effect of Fe additions on phases that are formed after synthesis in the TiO2–Al–C system. Before experimental tests, thermodynamic calculations were performed to determine the range that Fe can be added to the reaction and remain self sustaining. The experimental observations showed that the reaction became unstable when the amount of Fe was changed from 15 to 20 wt.%, which was considerably lower than that was predicted by thermodynamic calculations. X-ray diffraction analysis indicated that novel metallic materials Fe3Al, TiC and Al2O3 are the main phases formed in the products and additions of Fe decreased the lattice parameter of TiC. Scanning electron and optical microscopy examinations showed that the addition of Fe decreased TiC particle size and changed their growth controlling mechanism. The Vickers hardness are anhanced with the addition of the iron to the particle reinforced metal-matrix composites in the TiO2–Al–C system.

Keywords: High Pressure High Temperature (HPHT); TiO2–Al–C–Fe system, Novel metallic materials, TiC growth mechanism.

1

Congrès général SFP 2017

Anti-tunnel effect: when climbing a mountain is faster than taking the tunnel

Marie Chupeau1, Emmanuel Trizac1, Alexei Chepelianskii2 1 Laboratoire de Physique Théorique et Modèles Statistiques, UMR 8626, UPSud, Orsay 2 Laboratoire de Physique des Solides, UMR 8502, UPSud, Orsay

Figure 1: Overdamped Brownian particle in

a one-dimensional potential

If you were asked to choose the fastest way between climbing a steep mountain and crossing it along a tunnel, you would certainly pick the tunnel. For an overdamped Brownian particle however, the choice is not that trivial. Indeed, if we consider such a particle in a one-dimensional interval, with a reflecting wall at the origin and an exit at L (Fig.1), it has been shown1 that adding a very high triangular mountain next to the origin can substantially lower the mean exit time of the particle. But besides this preliminary work, this strange effect has not been investigated.

Here, we focus on various aspects of this “anti-tunnel effect”. How to design the shape of the

potential barrier in order to minimize the mean exit time of the particle? What does this effect become in higher dimensions? Is it limited to the overdamped regime, or does it still exist when the inertia of the particle is taken into account?

1. V. Palyulin and R. Metzler, How a finite potential barrier decreases the mean first-passage time, Journal of Statistical Mechanics: Theory and Experiment, 03, L03001 (2012)

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Pour les posters : Division matière condensée Congrès général SFP 2017

RESONANT INJECTION OF INGAAS PLASMONS

S. Cosme1, A. Vasanelli1, T. Laurent1, G. Frucci1, Y. Todorov1, G. Beadoin2, I. Sagnes2, and C. Sirtori1

1Université Paris Diderot, Sorbonne Paris Cité, LaboratoireMatériauxetPhénomènesQuantiques

2Laboratoire de Photoniqueet de Nanostructures, CNRS, 91460 Marcoussis, France Spontaneous emission is usually related to a transition between electronic states and is characterized by a lifetime proportional to ω-3, where ω is the emission frequency. This dependence on ω hinders the realization of efficient light-emitting devices in the mid and far infrared wavelength range, as the spontaneous emission time is several orders of magnitude longer than the typical non-radiative mechanisms. In this context, the superradiant nature of collective electronic excitations in highly doped semiconductor layers is particularly appealing for the realization of efficient mid-infrared light-emitting devices. Indeed, the radiative lifetime of these excitations (i.e. the plasmons) depends on the electronic density and it can be much shorter than that of a single electron transition, even shorter than the non-radiative lifetime [1]. However, collective excitations cannot be simply interpreted by a transition between two electronic states and as such are very difficult to excite through a DC current. Indeed the nature of the interaction between plasmons and individual electrons carrying a certain kinetic energy is a rather complicated theoretical problem that has still to be solved. In this work we present a semiconductor device in which plasmons are directly excited by a vertical current impinging on a two dimensional electron gas [2,3]. Fig. 1a presents the conduction band profile of our sample. A potential well is created by inserting a highly doped GaInAs layer between undopedGaInAs layers, without employing any barrier material. Under the application of a voltage bias, electrons are injected in the potential well region at high velocity, thanks to the presence of an AlInAs barrier. Fig. 1b presents an electroluminescence spectrum measured at 78K through a polished facet. It shows a clear resonance at the energy of the plasmon. This result opens the way towards the realization of optoelectronic devices based on many-body excitations.

[1] T. Laurent et al. Phys. Rev. Lett.115, 187402 (2015). [2] T. Laurent et al. Appl. Phys. Lett. 107, 241112 (2015) [3] K. Kempa, E. Gornik, K. Unterrainer, M. Kast, and G. Strasser, Phys. Rev. Lett. 86, 2850 (2001)

1

Figure 1: (a) Conduction band profile of the sample. (b) Electroluminescence spectrum measured at 78K and at 25° internal angle of light propagation. The inset presents a sketch of the geometry used for angle resolved electroluminescence measurements.

O1 Congrès général SFP 2017

Strong Coupling of a Single Spin to a Superconducting Circuit

J.F. Silva Barbosa1, P. Campagne-Ibarcq1, P. Jamonneau1,2, S. Probst1, Y. Kubo1, A. Bienfait1, T. Teraji3, S.Pezzagna4, D. Vion1, R. Heeres1 and P. Bertet1

1Quantronics Group, SPEC, CEA-Saclay, France, 2LPQM, ENS de Cachan, France, 3NIMS, University

of Tsukuba, Japan, 4Department of Nuclear Solid State Physics, Leipzig University, Germany

Our project aims at detecting a single

spin using magnetic resonance techniques by

coupling it to a high quality factor

superconducting resonator. The electron spins of

choice are shallow (~15 nm) implanted single

Nitrogen-vacancy (NV) centers in an ultrapure

isotopically-enriched C12 diamond layer. After

characterization at room temperature using a

confocal microscopy, an Aluminium microwave

resonator is fabricated on top with a nanometric

constriction (width ~40 nm) carefully aligned to a

pre-selected NV center.

Figure.1: Sketch of our method

The constriction enhances the magnetic field generated by the microwave frequency current, and therefore

allows to increase the spin-resonator coupling strength to a range of 1 – 5 kHz. Microwave-only

measurements in a dilution refrigerator at 20mK should then allow to observe a spin-echo signal from a

single spin.

1

Division de la Matière condensée Congrès général SFP 2017 Ultrafast structural dynamics of metallic materials probed by photoelectron

spectroscopy

M. de Anda Villa1, A. Lévy1, J. Gaudin2, S. Cervera1, B. Chimier2, P. Combis5, D. Descamps2, N. Fedorov2, R. Grisenti3, Y. Ito4, E. Lamour1, S. Macé1, P. Martin2,

S. Petit2, C. Prigent1, V. Recoules5, J.P. Rozet1, L. Soulard5, S. Steydli1, M. Trassinelli1, K. Ueda4, L. Videau5, and D. Vernhet1

1 Institut des Nanosciences de Paris, Sorbonne Universités UPMC Paris 6, 75252 Paris Cedex 05, France 2 Université de Bordeaux, CEA, CNRS, CELIA, 33400 Talence, France 3 Institut für Kernphysik, J.W. Goethe Universität Max-von-Laue-Str. 1, 60438 Frankfurt (M), Germany 4 Tohoku University, Sendai 980-8577, Japan 5 CEA, DAM, DIF, 91297, Arpajon, France

This work aims to study phase transitions in metallic materials upon excitation by femtosecond laser pulses1 using time-resolved photoelectron spectroscopy (PES). When irradiated by short infrared laser pulses, the outermost electrons of a metallic material heat rapidly (~100 fs) creating a very strong out-of-equilibrium state of matter. Next, the energy is transferred to the lattice through electron-phonon interactions in a timescale of a few picoseconds, modifying the atomic structure2 (phase transition, disorder, rearrangements). Then, the solid cools down in a few hundreds of picoseconds leading also to lattice modifications. The difficulties in modeling this specific regime of matter arise from its intrinsic out-of-equilibrium character: Matter properties such as electron-phonon coupling, electronic, ionic thermal conductivity and heat capacity remain poorly known3.

In this context, pump/probe time-resolved experiments with sub-picosecond resolution may help to improve our understanding of the aforementioned processes and material properties in these extreme density and temperature conditions. The relaxation of matter can be observed in time by monitoring the PES spectra of the metal’s valence band (VB) at different time after excitation. In Fig. 1, the results using a 2 ps pump pulse and the High Harmonic Generation 40 eV beamline of the CELIA laboratory as a probe are presented4. The duration of the pump pulse is restricted by the probe pulse photon energy. In order to reach femtosecond timescales, we have developed and characterized a new beamline that delivers femtosecond pulses up to 100 eV. Further improvements to the experiment, which will open perspectives in studying different materials at different excitation intensities, will be discussed at the conference.

1. J. Chen et al. Time-resolved structural dynamics of thin metal films heated with femtosecond optical pulses 108, p

18887 PNAS (2011) 2. S. Daraszewicz et al. Structural dynamics of laser-irradiated gold nanofilms 88, p 184101 Phys. Rev. B (2013) 3. L. Waldecker et al. Electron-Phonon Coupling and Energy Flow in a Simple Metal beyond the Two-Temperature

Approximation 6, p 021003 Phys. Rev. X. (2016) 4. A. L'Huillier et al. High-order harmonic generation in rare gases with a 1-ps 1053-nm laser 70, p 774 Phys. Rev. Lett.

(1993)

Figure 1. VB evolution of 1µm gold layer upon femtosecond laser excitation.

Titre

Synthesis and characterization of FeSe nanoparticles obtained by high-energy ball milling

A. Chebli1, A. Djekoun1, N. Boudinar1, M. Benabdeslem1, B. Bouzabata1

1Laboratoire de Magnétisme et de Spectroscopie des Solides Université Badji Mokhtar Faculté des

Sciences B. P: 12 (23000) ANNABA –Algérie

Recently enough attention was given to iron selenide because of the unusual

structure and electronic properties of transition metal chalcogenides. Iron selenide system

presents two homogeneous and stable phases, α-FeSe and FeSe2 [1,2], and a variety of

structures. Fe–Se compound attracts more and more attention due to its wide application in

optical electronic, photovoltaic, magnetic devices and solar cell. Several methods have been

attempted to prepare the iron selenide: molecular beam epitaxy, ball milling, selenisation of

evaporated iron thin films, and selenisation of amorphous iron oxide thin films predeposited

by spray pyrolysis. In all these methods, enormous amount of energy is required for

materials formation and is time consuming. In addition, when there is a large difference in the

melting points of constituents iron (1535 °C) and selenium (217 °C), it becomes difficult to

obtain FeSe compound with desired stoichiometry by these techniques.

The mechanical alloying (MA) method has been considered the most powerful tool for

nanostructured materials, and it provides numerous advantages, because of its simplicity,

relatively inexpensive equipment, and the possibility of producing large quantities, that can

be scaled up to several tons.

Morphological, structural and thermal changes during milling were analyzed by scanning

electron microscopy (SEM) coupled with EDAX microanalysis, X-ray diffraction (XRD) and

differential scanning calorimetry (DSC). With milling time up to 6 h, combined XRD patterns

and DSC show α-Fe and also some amorphous selenium. For the samples milled between

10 and 20 h, the orthorhombic FeSe2 and β-FeSe hexagonal nanometric phases are formed

and the volume fraction of the α-Fe phase decreases. For 33 and 52 h of milling (fig.1), the α-

Fe phase is completely gone and the emergence of new phase, also in nanometric scale, a

typical of Fe7Se8 phase.

[1] B.X. Yuan, X.Q. Hou, Y.L. Han, W.L. Luan and S.T. Tu, New J Chem. 36, 2101 (2012).

[2] B. Ouertani, J. Ouertfelli, M. Saadoun, B. Bessais, H. Ezzaouia and J.C.Bernède, Sol. Energy Mater. Sol. Cells. 87, 501 (2005)

Congrès général SFP 2017 DMC

Condensation and evaporation of fluids in nanopores : an optical study

Victor Doebele1, Panayotis Spathis 1, Laurent Cagnon1, Pierre-Etienne Wolf 1 and Etienne Rolley 2

Grenoble Alpes-CNRS, 25 Avenue des Martyrs, 38042 Grenoble, France 2 LPS-ENS, 24 rue Lhomond, 75231 Paris Cedex 5

In nanoporous materials, the process of fluid condensation/evaporation is hysteretic. This hysteresis may arise from effects at the pore level, collective effects due to inter-pores connections, or disorder. We recen-tly started a project aiming at studying hys-teresis at the single pore level by using thin (60 microns) porous alumina membranes as model systems.

Figure : Liquid fraction and light transmission during a cycle of hexane condensation/evaporation in a porous alumina membrane.

Such membranes, fabricated by anodization of aluminum wafers, present parallel, indepen-

dent, cylindrical pores, the diameter of which can be tuned in the 10-100 nm range with a narrow dispersion. Condensation and evaporation as a function of the fluid pressure is tracked by measu-ring the fluid content by optical interferometry, from the phase shift between beams reflected by either face of the membrane. Experiments performed at LPS-ENS (visible light interferometry, as described by Casanova [1]) and Institut Néel (monochromatic interferometry) on the same mem-branes and using different alkanes have shown that the fringes contrast strongly degrades during the condensation process. This is due to strong light scattering, the transmission dropping to less than 0.3 % during condensation (and 3% during evaporation) . Such a decrease implies that these processes are not homogeneous at the microscopic scale, either parallel to the pores or perpen-dicular. This unexpected result could be the first direct evidence that, even in such nearly ideal systems, disorder along the pore axis could play a central role in the condensation and evapora-tion processes, a fact suspected but never directly proven. 1. F. Casanova, C. E. Chiang, C.-P. Li, and I. K. Schuller. Direct observation of cooperative effects in capillary condensation: The hysteretic origin. Applied Physics Letters, 91(24):243103, 2007

1

Congrès général SFP 2017 Fondamentaux et applications en nanophotonique résonnante

Directional perfect absorbers without any photonic structure

B. Dailly 1, A. Vasanelli 1, S. Huppert1 , G. Frucci1, Y. Todorov1, G. Beaudoin2, I. Sagnes2 and C. Sirtori 1

1 Université Paris Diderot, Sorbonne Paris Cité, Laboratoire Matériaux et Phénomènes Quantiques 2 Laboratoire de Photonique et Nanostructures, CNRS, 91460 Marcoussis, France

Intersubband absorption in a quantum well is usually described by using perturbation theory. In

this framework, the absorption spectrum is a Lorentzian function, with an amplitude proportional to the electronic density in the quantum well [1]. In this work we show that this perturbative picture breaks down in highly doped quantum wells. In order to create thermal emitters using highly doped quantum wells, we studied the absorption of such system. Emission and absorption are linked via the Kirchhoff law.

We performed angle resolved reflectivity measurements on two samples: a single highly doped quantum well of 45nm (SQW) and a sample with six 45nm quantum wells separated by 15nm barriers (MQW), both with a metallic mirror on the top surface. Figure 1a shows absorptivity spectra extracted from these measurements on the two samples at two different angles. At 6° the two spectra present a single resonance, associated with a collective mode of the electron gas, the multisubband plasmon [2]. The spectra from the two samples have identical shape and their amplitude is proportional to the number of QWs effectively coupled with the electromagnetic field, in agreement with a perturbative treatment of the light-matter interaction. At 35° the absorptivity of SQW sample is almost unity and greater than that of MQW sample, whose spectrum is, at this angle, radiatively broadenend. Figure 1b presents the peak absorptivity of the two samples as a function of the angle, showing similar behavior. Perfect absorption without any photonic structure is observed for the two samples, at an angle that depends on the ratio between radiative and non-radiative broadening [3]. These counter-intuitive properties of the optical spectra can be understood by considering that plasmons are non-perturbatively coupled with free space photons [4].

Figure 1 : (a) Absorptivity spectra extracted from reflectivity experiments of MQW (blue) and SQW (red)

samples at two different angles. (b) Peak absorptivity as a function of the angle for the two samples.

Continuous lines present the results of our quantum model.

1. M. Helm, Intersubband Transitions in QuantumWells. Physics and Device Applications I, vol. 66 of Semiconductor and Semimetals (Academic Press, 2000).

2. A. Delteil, et al. Phys. Rev. Lett. 109, 246808 (2012). 3. S. Huppert, et al., ACS Photonics 2, 1663 (2015) 4. S. Huppert, A. Vasanelli, G. Pegolotti, Y. Todorov,C. Sirtori, Phys. Rev. B 94, 155418 (2016).

0.1

0.2

150 180 2100.0

0.3

0.6

0.9

= 35°

Ab

so

rptivity

= 6°

Energy (meV)

MQW

SQW

(a)

O1 Congrès général SFP 2017

ULTRAFAST DYNAMICS OF PHASE CHANGE MATERIAL PROBED BY FREQUENCY DOMAIN INTERFEROMETRY.

J. Gaudin1, I. Papagiannouli1, V. Blanchet1, D. Descamps1,

C. Fourment1, S. Petit1, N. Bernier2, P. Noé2

1 CEntre Lasers Intenses et Applications, 43 rue Pierre Noailles, 33405 Talence, France 2 Univ. Grenoble Alpes, CEA, LETI, MINATEC Campus, F-38054 Grenoble, France

Chalcogenide Phase-Change Materials (PCMs), mainly GeSbTe-based alloys, have already been widely used for optical data storage (DVD-RAM, CD-RW) thanks to their unique reversible fast amorphous to crystalline phase transition characterized by an unique change in optical and electrical properties. PCMs are now studied aiming at developing innovative non-volatile memories1. The interaction of PCMs with a fs light pulse has attracted significant attention due to fundamental interest since the possible non-thermal amorphous↔crystal phase transition could be used as a process to drive the phase change above the thermal “speed limits”2.

Frequency domain

interferometry (FDI)3 is a

pump-probe experiment

that gives access to the variation of

the refractive index of a material. A pump pulse (25 fs, 800 nm, 1kHz) is used to trigger a phase transition. The probe beam is made of two pulses (120 fs, 532 nm) delayed by 9 ps in our case which are focused on the pump/sample interaction point. The intensity variation and phase shifts of the interfering probe pulses (right image in the fig. 1) can be used to retrieve variations of the optical constant of the heated material. The interference pattern is simultaneously measured for the S ans P polarization independently.

Experiments on prottypical PCMs (Ge2Sb2Te5, GeTe) thin films have been conducted in the tenth of mJ/cm2 fluence range allowing us to trigger the amorphous to crystal phase transition. Dynamics on the sub-ps time scale shows a very rapid switch mainly attributed to the real part of the refractive index. The polarisation resolved FDI allows us to also foster informations on the behaviour of the surface. A clear phase shift is attributed to a contraction, in the nm range, and the sub-ps time scale. 1.P. Noé et al., Phase Change Materials for Non-Volatile Memory devices: From Technological Challenges to Materials Science Issues, Topical Review in Semicond. Sci. Technol., to be published (2017). 2 D. Loke et al. Breaking the Speed Limits of Phase-Change Memory Science 336, 1566 (2012) 3 J.P. Geindre et al., Frequency-domain interferometer for measuring the phase and amplitude of a femtosecond pulse probing a laser-produced plasma Optics Letters 19, 1997 (1994).

FIgure 1 : FDI set-up (left), typical measured inteferogram (right)

Division matière condensée Congrès général SFP 2017

Study of the crack propagation in multiphases ceramic composites

obtained by reaction sintering

Farid.GHELDANE, Seddik.BOURAS

Laboratory of Advanced Materials, Department of physics, University Badji Mokhtar Annaba, Algeria.

Zirconia particles can be added to the matrix to overcome the brittleness inherent in ceramics

materials, thereby strengthening the material through tetragonal-monoclinic phase transformation of the

zirconia. This work focuses on the study of Crack propagation behaviour of alumina mullite zirconia

composites that were obtained by reaction sintering of alumina and zircon. This material is investigated

under monotonic and cyclic loading by means SENB bending method. This material show R-curve effects,

i.e. an increase in crack growth resistance with increasing crack depth. The morphological study showed

that the resistance of the crack propagation is mainly connected to the crack bridging. The value of

bridging stress is in good agreement with the literature.

The toughening mechanisms provided by zirconia and mullite inclusions, based not only on the R-curve

behaviour but also on the analysis of the fracture surface, are also discussed in this work.

O1 Congrès général SFP 2017

X-Ray Study of Ni50Al50 nanostructured powders

M. GHERIB1, A. OTMANI 1 Ecole Supérieure des Technologies Industrielles, 23000 Annaba, ALGERIA

Nanostructured powders Ni-50wt%Al were prepared by mechanical alloying under argon atmosphere from elemental Ni and Al powders, using a planetary ball mill (type Fritsch P7) for different times (0.5-24h).). Microstructural and structural of the final products are characterized by X-rays diffraction (XRD) and Scanning electron microscopy (SEM). The results of the XRD shows the formation of the B2 (Ni Al) phase after 2 hours of milling. The crystallite size refinement of the final product down to the nanometer scales when the milling time increased and attained 17 nm in Ni50Al50 system at 24 hours. This decrease of crystallite size is accompanied by an increase in the interval level strain. The kinetics of Al dissolution during the milling process of Ni50Al50 system can be described by two regimes characterized by different values of Avrami parameters which are calculated by using the Johnson–Mehl–Avrami formalism.

Pour les colloques : Des fermions de Majorana à la matière topologique Congrès général SFP 2017

Are odd-parity states in Andreev Quantum Dots always a nuisance?

M. F. Goffman 1, L. Tosi 1, H. Pothier1, C. Urbina 1, P. Krogstrup 2and J. Nygård 2 1 Quantronics group, SPEC, CEA, CNRS, Université Paris-Saclay, CEA Saclay, France 2 Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Denmark.

An Andreev quantum dot (AQD) is a phase-biased superconducting weak link in which discrete

Andreev bound states develop. In particular, a single-channel AQD accommodates one Andreev state

that can be occupied by either zero, one or two quasiparticles. In a recent cQED experiment on one-

atom weak links we demonstrated the coherent manipulation of the two-level system formed by the

even states [1]. Moreover, as a common feature to other superconducting devices, the single-occupied

state of the AQD was also observed. We have focused on the role of the odd state in the dynamics of

the AQD and I will present our results on the time-domain study of the parity jumps observed due to

quasiparticle poisoning. Although the odd states are spin-degenerate, the fact that they are long-lived

states makes them appealing for a qubit. I will present our recent progress in the realization of a spin-

AQD using a gated InAs-nanowire where degeneracy can be lifted by the combination of strong spin-

orbit coupling and a Zeeman field. We show that quasi-ballistic weak links can be obtained, an

important requirement to achieve single-spin manipulation.

Work done in collaboration with P. Senat, P. F. Orfila, P. Bertet, P. Joyez, D. Vion, D. Esteve, from the Quantronics group. [1] C. Janvier et al., “Coherent manipulation of Andreev states in superconducting atomic contacts” Science 349, 1199 (2015), arXiv:1509.03961

1

Division de la matière condensée Congrès général SFP 2017

Surface chemistry of colloidal surfactant-free gold nanoparticles

A. Lévy1, J. Gaudin2, M. Trassinelli1, D. Amans3, M. De Anda Villa1, J. Bozek4, V. Blanchet2, S. Cervera1, R. Grisenti5, E. Lamour1, S. Macé1, C. Nicolas4,

I. Papagiannouli1, M. Patanen6, C. Prigent1, J.P. Rozet1, S. Steydli1, D. Vernhet1 1 Institut des Nanosciences de Paris, Sorbonne Universités UPMC Paris 6, 75252 Paris Cedex 05, France 2 Université de Bordeaux, CEA, CNRS, CELIA, 33400 Talence, France 3 Univ Lyon, Université Claude Bernard Lyon 1, UMR5306 CNRS, Institut Lumière Matière, F-69622, Villeurbanne, France 4 Synchrotron SOLEIL, L’Orme des Merisiers, Saint-Aubin, BP 48, F-91192 Gif-sur-Yvette Cedex, France 5 Institut für Kernphysik, GSI - Helmholtz Center for Heavy Ion Research, J.W. Goethe Universität Max-von-Laue-Str. 1, 60438 Frankfurt (M), Germany 6 University of Oulu, Department of Physics, 90014 Oulu, Finland

Matter at the nanoscale level is at the center of several scientific domains because of their

promising applications in medical and technological fields1,2. The nanoparticle (NP) surface state is of primary importance for the development of these fields due to their sensitivity to the composition/structure of the NP surface. Among the various materials, Au is mostly studied owing to its noble character and low toxicity. Au NPs used in biomedical-oriented studies are usually produced by wet chemical reduction3, which requires stabilization agents to control their size and prevent their agglomeration. These ligands can be hardly removed and interfere with a further functionalization. Another promising NP synthesis technique, based on laser ablation of solids in liquids4, provides ligand-free NPs. However, NPs immersed in a solvent strongly interact with their environment leading to a modification of their surface properties. This environment-NP interaction plays a key-role in the colloidal stability, which is governed by the surface charge of the NPs. The present study addresses this question to depict a clear picture of the origin of the colloidal stability. In order to avoid any substrate influence, free standing NPs are probed by synchrotron radiation. Photoelectron spectroscopy is used as surface-sensitive diagnostic for the NP surface characterization. This experiment has been performed at the PLEIADES beamline of SOLEIL facility. Au 4f and valence band, probed for colloids in acetone, exhibit a partial oxidation of gold surface atoms.The latter, responsible for a negative surface charge, leads to electrostatic repulsion of NPs and consequently to colloidal stability. Beyond a proof-of-principle for free-standing gold NP beam generation, this experiment opens perspectives for the surface characterization of Au colloids as a function of solvent nature, salinity, PH level. 1. S. Petersen et al. J. Phys. Chem. C 2011 115 5152 2. D. Widmann et al. Acc. Chem. Res. 2014 47 740 3. R. Sardar et al. Langmuir 2009 25 13840 4. S. Barcikowski et al. Phys. Chem. Chem. Phys. 2013 15 3022

1

Figure 1 Figure 1: Au 4f probed at 200 eV. Au 4f levels exhibit two components associated to Au(0) and Au(I) oxidation degrees.

Pour les colloques :Magnétisme frustré Congrès général SFP 2017 Pour les posters : Division ou commission SFP associée

Long-period smectic-like magnetic structures inMn1-x(Co,Rh)xGe

N. Martin1,*, M. Deutsch2, G. Chaboussant1, F. Damay1, P. Bonville3, L.N. Fomicheva4,

A.V. Tsvyashchenko4,5, U.K. Rössler6 and I. Mirebeau1 1. Laboratoire Léon Brillouin CEA-CNRS, Univ. Paris-Saclay, 91191 Gif-sur-Yvette, France

2. Université de Lorraine, CRM2, UMR UL-CNRS 7036, 54506, Vandoeuvre-lès-Nancy, France 3. SPEC, CEA-CNRS, Université Paris-Saclay 91191 Gif-sur-Yvette, France

4. Vereshchagin Institute for High Pressure Physics,142190, Troitsk, Moscow, Russia

5. Skobeltsyn Institute of Nuclear Physics, MSU, Vorob’evy Gory 1/2, 119991 Moscow, Russia

6. IFW Dresden, PO Box 270116, 01171 Dresden, Germany

Despite tremendous experimental and theoretical activities in the field of magnetic skyrmions, the effect

of quenched disorder on ground-state properties of their host chiral magnets has been scarcely studied up

to now. It is however known from the physics of liquid crystals that novel properties may be expected

when tuning the content of chiral species within a smectic or cholesteric parent compound. In this frame,

we present a study of Mn1-x(Co,Rh)xGe alloys. At low temperature, pure MnGe hosts short wavelength spin

helices (Fig. a) while CoGe and RhGe are examples of Pauli paramagnet and unconventional

superconductor, respectively. Upon substitution of Mn by Co and Rh, the helical wavelength is found to

increase by a factor ≈ 30, while the ordered magnetic moment remains large (Fig. b,c). Above a doping

level x ≈ 0.45 (Co) and 0.25 (Rh), neutron small-angle scattering suggests the formation of magnetic

dislocations, whose core is composed of skyrmion-antiskyrmion pairs (inset of Fig. a). Such behavior is

strongly reminiscent of the twist grain boundary phase observed at the interface between cholesteric and

smectic liquid crystalline phases. Moreover, we evidence a strong correlation between unit cell volume

and ordered magnetic moment, in agreement with pressure-induced spin state transitions recently

evidenced in MnGeby neutron and X-ray scattering. Taken together, our results reveal new ways for

tuning the microscopic properties of chiral magnets and prompting the stabilization of compact topological

magnetic defects.

Figure 1: Effect of Rh/Co

doping on MnGe as seen by small angle neutron scattering 1.N. Martin et al.,arXiv:1702.06511 (2016)

1

heat transfer characteristics of nanofuid flow around a elliptical

cyinder

S.MIZANI*,H.ZERRADI, A.DEZAIRI

Laboratory of condensed matter, faculty of sciences Ben M`sick (URAC.10). University Hassan II- Mohammedia Casablanca, Morocco

*Corresponding authors: soufiya.mizani@gmail.com,

Abstract:

This work represents the results of extensive numerical simulations of 2D nanofluid flow around heated elliptical cylinder with different incidence angle and aspect ratio. The continuity and momentum equations have been numerically solved using a SIMPLE algorithm.Two types of nanofluids consisting of Al2O3 and CuO nanoparticles with base fluids of water and ethylene glycol mixture60:40 (by mass) were selected to evaluate their effect on the flow over elliptical cylinder, also their superiority over conventional fluids.The thermo-physical parameters of nanofluid have been estimated using the theory of one fluid phase, a contemporary correlations of thermal conductivity and viscosity of nanofluids have been used in this paper, which are functions of particle volumetric concentration as well as temperature. The results of heat transfer characteristics of nanofluid flow over elliptical cylinder reveled clear improvement comparing with the base fluids. The obtained results have been presented to get further insight for easy applications. Key words: Nanofluid, Fluid flow, Elliptical cylinder, Heat transfer

Structural, magnetic and magnetocaloric properties of Pr0.6Sr0.4-xNaxMnO3 (0≤ x ≤0.1) have been

investigated. Our samples were elaborated using the conventional ceramic method at high

temperature. Rietfeld refinement of the X-ray diffraction patterns show that all our samples are

single phase and polycristallize in the orthorhombic sructure with Pbnm space group. The sodium

doping leads to a decrease in the unit volume.

Magnetization measurements versus temperature in a magnetic applied field of 50mT indicate that

all our investegated samples present a paramagnetic to ferromagnetic behavior with decreasing

temperature. The value of the Curie temperature decreases from 340K for the parent sample

Pr0.6Sr0.4MnO3 to 290K for Pr0.6Sr0.3Na0.1MnO3. A large magnetocaloric effect MCE has been observed

in all our compounds. The value of maximum entropy chage is found to be 3.87JK-1Kg-1for X= 0.05 in

magnetic applied field of 5T. for Pr0.6Sr0.3Na0.1MnO3. The RCP value is found to be equal to 141.9JKg-1

in a magnetic applied field change of 3T.

Keywords: manganites, magnetocaloric, magnetic refrigeration.

O1 Congrès général SFP 2017

Ballistic edge states in Bismuth nanowires revealed by SQUID interferometry

Anil Murani1, Alik Kasumov1, Shamashis Sengupta1, François Brisset2, Raphaëlle Delagrange1

, Alexei Chepelianskii1, Richard Deblock1, Sophie Guéron1, Hélène Bouchiat1

1 Laboratoire de Physique des Solides, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91405 Orsay Cedex, France 2 IInstitut de Chimie Moléculaire et des Matériaux d'Orsay, Univ. Paris-Sud, Université Paris-Saclay, CNRS, 91405 Orsay Cedex, France

Spin-orbit interactions are known to have drastic effects on the band structure of

heavy-element-based materials. Celebrated examples are the recently identified 3D and 2D topological insulators. In those systems transport takes place at surfaces or along edges, and spin-momentum locking provides protection against (non-magnetic) impurity scattering, favoring spin-polarized ballistic transport [1]. We have used the measurement of the current phase relation of a micrometer-long single crystal bismuth nanowire connected to superconducting electrodes, to demonstrate that transport occurs ballistically along two edges of this high-spin-orbit material. In addition, we show that a magnetic field can induce to 0-pi transitions and phi0-junction behavior, thanks to the extraordinarily high g-factor and spin orbit coupling in this system, providing a way to manipulate the phase of the supercurrent-carrying edge states [2].

Finally, I will disclose microwave spectroscopy measurement of the dynamical susceptibility in this system are initiated, that could reliably demonstrate the property of protection against disorder according to numerical simulations [3]. 1. C.L. Kane, E.J. Mele, Phys. Rev. Lett. 95 (2005), 226801 2. Anil Murani, et. al., arXiv:1609.04848 3. Anil Murani, Alexei Chepelianskii, Sophie Guéron, Hélène Bouchiat, arXiv:1611.03526

Pour les colloques : Congrès général SFP 2017 Pour les posters : DMC

Physique statistique hors-équilibre, mesures dans dans les gaz granulaires.

A. Naert 1, J.-Y. Chastaing 1, J.-C. Géminard 1

1 Laboratoire de Physique, ENS-Lyon, 69007, Lyon, France

Il est apparu récemment qu'un « réservoir d'énergie stationnaire hors-équilibre » se comporte, à bien des égards de la même manière que le thermostat d'équilibre idéal habituellement impliqué en physique statistique. L'un de nos objectifs est d'étudier expérimentalement dans quelle mesure cette analogie persiste.– Nous nous concentrons sur un mobile « brownien 1D d'échelle macroscopique » : un rotor d'axe vertical qui sert de sonde, immergé dans un gaz granulaire dilué. Le gaz granulaire, agité indépendamment, joue le rôle du thermostat1. La température est définie et mesurée grâce à deux méthodes distinctes mais cohérentes, basées sur l'utilisation heuristique du théorème de fluctuation de Gallavotti-Cohen1 pour l'une, et du Théorème Fluctuation-Dissipation2 pour l'autre. L'accord est meilleur que 10%. Le concept de « température hors-équilibre » est intéressant en soi, comme un premier pas pour décrire de tels systèmes avec le langage de la thermodynamique.

– En outre, nous avons étudié les propriétés de transport d'énergie entre deux systèmes faiblement couplés par leurs sondes de manière électromagnétique, plongées chacune dans les bains granulaires de température ou de densité différente3,4. – La comparaison avec le mouvement brownien permet encore de mesurer la viscosité et la diffusivité du gaz granulaire, même très raréfié. Nos observations rejoignent étonnamment bien ce qui est attendu par la théorie cinétique des gaz5.

Figure : système expérimental (diamètre cellule 5 cm, hauteur 6 cm, ~ 300 billes de 3 mm, ici au repos, pale de 2 cm x 2 cm).

1. A. Naert. EPL, Experimental study of work exchange with a granular gas: The viewpoint of the Fluctuation Theorem, 97(2):20010, 2012.

2. J.-Y. Chastaing, J.-C. Géminard, A. Naert, Two methods to measure granular gas temperature, soumis à J. Stat. Mech.: Theory Exp. (2017)

3. C.-E. Lecomte, A. Naert, Experimental study of energy transport between two granular gas thermostats, J. Stat. Mech.: Theory Exp. (2014) P11004

4. J.-Y. Chastaing, J.-C. Géminard, A. Naert, Experimental study of energy exchanges between two coupled granular gases, Phys. Rev. E 94, 062110, (2016)

5. J.-Y. Chastaing, J.-C. Géminard, A. Naert, Experimental study of low-density granular-gas, à publier1

O1 Congrès général SFP 2017

Modélisation et simulation numérique de la propagation des fissures à la

surface de rail.

A. Nebgui1, M. Azouggagh1, O. Oussouaddi1,

M. Haterbouch2, A. Zeghloul3

1LEM2A, Faculté des Sciences de Meknès, Université Moulay Ismaïl, Maroc

2MAA, ENSAM, ENSAM de Meknès, Université Moulay Ismaïl, Maroc

3LEM3 UMR CNRS N°7239, Université de Lorraine - Metz, 57045, France

Résumé :

Cette étude porte sur l'étude de la fatigue de contact roue/rail. Le comportement du matériau est modélisé avec la loi de comportement de Chaboche-Lemaitre. L’endommagement est quantifié à l’aide du paramètre de fatigue de Jiang-Sehitoglu. La méthode de Miner est utilisée pour décrire la propagation de fissure. L'influence de plusieurs paramètres, à savoir la longueur initiale de la fissure, son orientation par rapport à la surface de roulement, le niveau du chargement, sur la vitesse de propagation des fissures de fatigue et le facteur d’intensité de contrainte (FIC) a été étudiée.

Mots-clés :

Fatigue de contact de roulement, Rail, propagation de fissure, MEF.

Congrès général SFP 2017

Room-temperature operation of a quantum well mid-infrared detector embedded in nano-antennae array at critical optical coupling

D. Palaferri1, Y. Todorov1, A. Bigioli1, A.Calabrese1, L. Chen2,

L.Li2, E.H. Linfield2, and C. Sirtori1

1 LaboratoireMatériauxetPhénomènesQuantiques, Université Paris Diderot – CNRS UMR 7162, 75205 ParisCedex 13, France

2 School of Electronic and Electrical Engineering, University of Leeds, Leeds LS2 9JT, United

Quantum Well Infrared Photodetectors (QWIP) represent avalid solution to the demand of fast and high sensitive

detection in the infrared and far-infrared spectral region (5µm < λ < 200µm) [1]: these devices use intersubband (ISB)

transitionsin a semiconductor quantum well (QW) superlattice (mainly ntype doped GaAs/AlGaAs) to generate

photocurrent.The mainissue related to QWIP is the high dark current which obliges towork at liquid nitrogen

temperature. Recently, wedemonstrated an antenna-coupled microcavity geometry forQWIP operating at mid-

infrared[2]and terahertz[3]frequencies,which enables an improved light coupling, a reduced darkcurrent and a higher

temperature performance. The benefit ofsuch plasmonic architecture on the detector performancerelies on the ability

to collect photons from an area muchlarger than device itself. We have designed the patchantennae array and

optically characterized so to achieve thecondition of critical coupling[4], i.e. all the incident photons areabsorbed by

the device array.We have characterized thedetector performances comparing it with a device made usingthe same

quantum well absorbing region, but processed into astandard 45° polished facet mesa2.The antenna-

coupledmicrocavity IR detector shows an enhancement of thebackground-limited temperature of more than 10K

andresponsivity values up to 1A/W, measured with a calibratedblackbody at 1000°C. Figure 1 (left) shows the

antennae arrayrealized by electron-beam lithography. Figure 1(right) shows the 200K and 300K photocurrent spectra

of the device. This is the first report of room temperature operation of a quantum well photoconducting device and is

important because with simple electrocooling the antenna-coupled device can have a competitivesensitivity for a broad

range of applications like fast lasercharacterization, infrared spectroscopy and heterodyne techniques.

Fig.1. (left)Antenna array withsize = 1.3µm and distance between each patchantenna a=2µm.

(right) Photocurrent spectra measured with a 1000°Cblackbody

1. H.C. Liu, Intersubband Transitions in Quantum Wells, ed. by HC Liu andFCapasso, AP San Diego (2000) 2. Y.N. Chen et al.,Appl. Phys. Lett. Vol.104 (2014) 3. D. Palaferri et al., Appl. Phys. Lett. Vol.106, 161102 (2015) 4. D. Palaferri et al., New J. Phys. 18, 113016 (2016)

1

Magnétisme frustré Congrès général SFP 2017

Antiferro-quadrupolar correlations in the quantum spin ice candidate Pr2Zr2O7

S. Petit1, E. Lhotel2,S. Guitteny1, O. Florea2,

J. Robert2, P. Bonville3, I. Mirebeau1, J. Ollivier4, H. Mutka4, E. Ressouche5

C. Decorse6, M. Ciomaga-Hatnean7, G. Balakrishnan7

1 Laboratoire Léon Brillouin, CEA, CNRS, Université Paris-Saclay, CEA-Saclay, F-91191 Gif-sur-Yvette, France 2 Institut Néel, CNRS and Univ. Grenoble Alpes, F-38042 Grenoble, France 3 SPEC, CEA, CNRS, Université Paris-Saclay, CEA-Saclay, F-91191 Gif-sur-Yvette, France 4 Institut Laue Langevin, F-38042 Grenoble, France 5 INAC, CEA and Univ. Grenoble Alpes, CEA Grenoble, F-38054 Grenoble, France 6 ICMMO, Université Paris-Sud, F-91405 Orsay, France 7 Department of Physics, University of Warwick, Coventry, CV4 7AL, United Kingdom

We present an experimental study of Pr2Zr2O7, considered as one of the quantum spin ice candidate, by means of magnetization measurements, specific heat and neutron scattering up to 12 T and down to 60 mK [1]. When the field is applied along the [111] and [1-10] directions, k=0 field induced structures settle in. We find that the ordered moment rises slowly, even at very low temperature, in agreement with macroscopic magnetization. Interestingly, for H // [1-10], the ordered moment appears on the so called chains only. The spin excitation spectrum is essentially inelastic and consists in a broad flat mode centered at about 0.4 meV with a magnetic structure factor which resembles the spin ice pattern (Fig 1). For H // [1-10] (at least up to 2.5 T), we find that a well-defined mode forms from this broad response, whose energy increases with H, in the same way as the temperature of the specific heat anomaly. We finally discuss these results in the light of mean field calculations and propose a new interpretation where quadrupolar interactions play a major role, overcoming the magnetic exchange. In this picture, the spin ice pattern appears shifted up to finite energy because of those new interactions. We then propose a range of acceptable parameters for Pr2Zr2O7. With these parameters, the actual ground state of this material would be an antiferroquadrupolar liquid with spin-ice like excitations.

[1] Phys. Rev. B 94 165153 (2016)

Figure 1 : Dynamical spin ice pattern in Pr2Zr2O7

O1 Congrès général SFP 2017

High sensitivity quantum limited electron spin resonance spectroscopy

Sebastian Probst1, Philippe Campagne-Ibarcq1, Audrey Bienfait1, Jarryd J. Pla2, Denis Vion1, Daniel Esteve1, Klaus Moelmer3, John J. L. Morton4, and Patrice Bertet1

1 Quantronics group, SPEC, CEA, CNRS, Université Paris-Saclay, CEA Saclay, France 2 School of Electrical Engineering and Telecommunications, University of New South Wales, Australia 3 Department of Physics and Astronomy, Aarhus University, Denmark 4 London Centre for Nanotechnology, University College London, United Kingdom

Electron spin resonance (ESR) spectroscopy is widely employed for the detection and characterization of paramagnetic species and their magnetic and chemical environment [1]. In a classical ESR spectrometer, the spins precess in an external magnetic field and emit small microwave signals into a cavity, which are amplified and measured. In this work, we make use of the toolbox of circuit quantum electrodynamics to boost the sensitivity of such a spectrometer by many orders of magnitude to the level of 102 spins/√Hz with a signal-to-noise ratio of 1 [2].

This is achieved by using a low impedance, high quality factor superconducting micro-resonator in conjunction with a Josephson parametric amplifier operated below 20 mK [3-5]. The energy relaxation time T1 of the spins (Bi donors in 28Si) is limited by the Purcell effect to 21 ms allowing fast repetitive measurements while the coherence time T2 is approximately 1.7 ms. This work is a step towards inductive detection of individual spins, which would be beneficial for quantum information processing and chemical analysis of materials at the single spin level.

[1] A. Schweiger and G. Jeschke, Principles of Pulse Electron Magnetic Resonance (Oxford University Press, 2001) [2] S. Probst et al., (in preparation) [3] X. Zhou et al., Physical Review B 89, 214517 (2014) [4] A. Bienfait et al., Nature Nanotechnology 11, 253 (2016) [5] A. Bienfait et al., Nature 531, 74 (2016)

1

Schematic of the experiment: The Bi spins are probed by microwave pulses at frequency ωs. The reflected echo signal is first noiselessly amplified by the Josephson parametric amplifier (JPA) operating in the phase sensitive mode where ωp=2ωs. After further amplification by commercial amplifiers, the signal is demodulated and digitized.

Pour les colloques : Congrès général SFP 2017 Pour les posters : Matière Condensée

Effets anisotropes 2D de l’interaction de liaisons pendantes sur le Si(100)

Mayssa Yengui1, Eric Duverger2, Philippe Sonnet3, Damien Riedel1

1 Institut des Sciences Moléculaires d’Orsay (ISMO), CNRS, Univ. Paris Sud, Université Paris-

Saclay, F-91405 Orsay, France 2 Institut FEMTO-ST, Univ. Bourgogne Franche-Comté, CNRS, 15B avenue des Montboucons, F-

25030 Besançon, France. 3Institut de Science des Matériaux de Mulhouse (IS2M), CNRS, UMR 7361, Université de Haute

Alsace, 3 bis rue Alfred Werner, 68057 Mulhouse, France.

L’étude et le contrôle des propriétés des boites quantiques à l'échelle atomique telles que les liaisons pendantes (DB) sur une surface fait l’objet

de thématiques de recherche à une échelle internationale. Les propriétés des DB permettent d'étudier différents processus à l'échelle du nanomètre comme des interrupteurs atomiques, le stockage d’une charge électrique, les interactions coulombiennes dans les automates cellulaires ou la formation d’états à liaison faible. Encore aujourd’hui, le contrôle de l’interaction des liaisons pendantes individuelles sur le silicium formant un dispositif bidimensionnel ayant une fonction définie reste un défi. Dans ce travail, nous avons exploité

l’interaction anisotrope entre DB sur la surface du Si(100):H afin d’ajuster leur degré d’hybridation. Ce processus proviennent des interactions entre le réseau en subsurface du silicium et les liaisons pendantes induisant des distorsions de Jahn-Teller et une réorganisation locale des charges. Un dispositif 2D prototype formant une étoile à trois branches a été conçu, dans lequel une charge supplémentaire peut être stockée de manière réversible. Les propriétés électroniques de ce dispositif sont alors semblables à celles d'un transistor en commutation. Nos résultats expérimentaux sont comparés avec succès à des simulations numériques utilisant la théorie de la fonctionnelle densité. La structure électronique de ce type de dispositif est tout particulièrement intéressante et permet une analogie avec l’interaction entre qubits que nous aborderons.

Figure 1 : anisotropie topographique de deux

dimers de liaisons pendantes sur le Si(100) à 9 K

O1 Congrès général SFP 2017

STRUCTURAL AND MICROSTRUCTURAL PROPERTIES OF Fe-

DOPED ZnO THIN FILMS BY SPRAY PYROLYSIS TECHNIQUE

SOURIA SAMMAR1, RACHID BENSALEM2

1. Laboratoire de Magnétisme et Spectroscopie des Solides, Département de Physique

2 . Université de Annaba B. P. 12 (23000) Algeria.

Microstructural, structural, and morphological propertiess of Fe-doped ZnO nanostructure semiconductor thin

films have been investigated by optical, SEM, XRD, and first principals computing. ZnO thin films grown on glass and Si

substrates by the pyrolysis method at 300 °C, and under atmosphere, have initial preferred (002) orientation. XRD

peak intensity decreased rapidly as the Fe- concentration is increased from 1 to 5 mol.%, despite the fact that lattice

parameters changed monotonously. Fe ions occupied the Zn sites without changing the original hexagonal wurtzite

structure. All Fe-doped ZnO films are nanometer scale with average grain size of 47 nm.

Poster Congrès général SFP 2017

Enhancement of charge transport induced by a cavity

David Hagenmüller1, Johannes Schachenmayer1, Stefan Schütz1, Claudiu Genes1,2, and Guido Pupillo1

1 IPCMS (UMR 7504) and ISIS (UMR 7006), University of Strasbourg and CNRS, 67000 Strasbourg, France 2 Max Planck Institute for the Science of Light, Staudtstraße 2, D-91058 Erlangen, Germany

We theoretically study the transport properties of electrons in a one-dimensional setup, wheninter-band transitions couple to the light field of a cavity mode that is close to the vacuum. It isshown that light-matter interaction can allow for a significant enhancement of steady-state chargecurrents in two bands that interact via emission and absorption of dressed photons. Ourinvestigations include the analysis of electronic transmissions and cavity photon spectra, obtainedby a non-equilibrium Green's function method. The results for the current enhancement arecompared with the ones of a quantum Master equation from which analytical results are deducedin specific limits. Besides presenting a proof-of-principle model for current enhancement, we showhow the latter can reach orders-of-magnitude in certain parameter ranges.

1 D. Hagenmüller, J. Schachenmayer, S. Schütz, C. Genes, and G. Pupillo, arXiv:1703.00803 (preprint).2 E. Orgiu, J. George, J. Hutchison, E. Devaux, J. F. Dayen, B. Doudin, F. F. Stellacci, C. Genet, J. Schachenmayer, C. Genes, G. Pupillo, P. Samori, and T. W. Ebbesen, Nature Materials 14, 1123 (2015).

1

Pour les colloques : Titre du colloque Congrès général SFP 2017 Pour les posters : Division ou commission SFP associée

Pico-ampere current sensitivity and diode like I-V Characteristics of FLC-CdSe QDs composites

Dharmendra Pratap Singh1, R. Douali1 and A. Daoudi2 1 Unite de Dynamique et Structure des Materiaux Moleculaires (UDSMM), Universite du Littoral Cote d’Opale (ULCO), 50 Rue Ferdinand Buisson, 62228 Calais Cedex, France 2 Unité de Dynamique et Structure des Matériaux Moléculaires, EA 4476, Université du Littoral Côte d'Opale, F-59140 Dunkerque, France

Figure 1 : AFM image of QDs dispersed FLC, (b) height profile, and I-V curves for (c) 0.1wt% and (d)

0.3wt% of QDs in FLC matrix. Cadmium selenide quantum dots (QDs) dispersed homogenous ferroelectric liquid crystal

(FLC) matrix is presented using atomic force microscopy. Here, QDs and FLC molecules have same order of dimension, therefore QDs uniformly fit in FLC matrix without perturbing the helical geometry and order parameters of host matrix. For the first time, pico–ampere current sensitivity has been recorded for FLC–QDs composites along with the 24% faster electro-optical response. This feature is most interesting for future touch–screen displays. The QD concentration dependent changes in I–V characteristics of FLC–QDs composites suggest their face–on to edge–on self assembly in FLC. These composites have shown their candidature for future touch–screen displays and soft matter based semiconducting energy storage devices. 1. S. Kumar and L. K. Sagar, Chem. Commun., 47, p12182 (2011). 2. D. P. Singh, S. K. Gupta, R. Manohar M. C. Varia, S. Kumar and A. Kumar, J. Appl. Phys., 116, p 034106 (2014). 3. J. Mirzaei, M. Reznikov and Torsten Hegmann, J. Mater. Chem., 22, p22350 (2012).

1

Congrès général SFP 2017 division PAMO-Matière Condensée

Critical behavior of 2D dissipative spin lattices R.Rota1, F. Storme1, N. Bartolo1, R. Fazio2,3, C. Ciuti1

1 Laboratoire Matériaux et Phénomènes Quantiques, Université Paris Diderot - Paris 7, Paris, France 2 ICTP, Trieste, Italy and NEST, Scuola Normale Superiore 3 Istituto Nanoscienze-CNR, Pisa, Italy

The study of dissipative phase

transitions is an emerging topic of research for non-equilibrium quantum many-body systems, which can be realized in artificial platforms using Rydberg atoms, semiconductor microstructures or superconducting circuits.

Recently, single-site mean-field1 and cluster mean-field2 studies of anisotropic Heisenberg model with incoherent spin relaxation have predicted unconventional magnetic phase transitions. A crucial problem is to explore the physical

properties of such dissipative transition beyond mean-field. By applying the corner-space renormalization method3 we have studied the critical behavior of such class of spin systems4.

We have been able to investigate the finite-size scaling and to calculate the critical exponent of the magnetic linear susceptibility. We show that the Von Neumann entropy increases across the critical point, revealing a strongly mixed character of the ferromagnetic phase. At the same time, the quantum Fisher information, an entanglement witness, exhibits a critical behavior at the transition point, showing that quantum correlations play a crucial role. Our results suggest that dissipative phase transition can share properties of both thermal and quantum phase transitions.

1 T. E. Lee, S. Gopalakrishnan, and M. D. Lukin, Phys. Rev. Lett. 110, 257204 (2013). 2. J. Jin, A. Biella, O. Viyuela, L. Mazza, J. Keeling, R. Fazio, and D. Rossini, Phys. Rev. X 6, 031011 (2016). 3. S. Finazzi, A. Le Boité, F. Storme, A. Baksic and C. Ciuti, Phys. Rev. Lett. 115, 080604 (2015). 4. R. Rota, F. Storme, N. Bartolo, R. Fazio and C. Ciuti, Phys. Rev. B 95,134431 (2017).

1

0.9 0.95 1 1.05 1.1 1.150

5

10

15

20

Jy/g

ca

v

6x6

5x5

4x4

3x3

2x2

2 3 4 5 610

0

101

L

cm

ax

av

Figure 1: Finite-size scaling of the magnetic susceptibility across the transition.

Inset: maximum value of the susceptibility as a function of the size L of the lattice.

Division Matière Condensée Congrès général SFP 2017 k-resolved band structure of CH3NH3PbI3hybridorganic-inorganicperovskite

M.-I Lee1, A. Barragán1, M. N. Nair1,2, V. Jacques1, D. Le Bolloc’h1, P. Fertey2, K. Jemli3, F. Lédée3, G. Trippé-Allard3, E. Deleporte3, A. Taleb-Ibrahimi2, and A. Tejeda1

1Laboratoire de Physique des Solides, CNRS, U. Paris-Sud, U. Paris-Saclay, Bat. 510, 91405 Orsay, France 2Synchrotron SOLEIL, Saint-Aubin, 91192 Gif-sur-Yvette, 3 Laboratoire Aimé Cotton, ENS Cachan, CNRS, U. Paris-Sud, U. Paris-Saclay, Bat. 505, 91405 Orsay, France Despite all the extensive work on hybrid organic-inorganic halide perovskites, their experimental band

structure measured with k-resolution has remained elusive. Such an experimental determination is a

necessary requirement for an accurate theoretical description and understanding of the system. The

impact of the structural phase transitions on the band structure in the operation temperature range of

solar cells needed also to be elucidated. Herein, we present the experimental determination of the band

structure of MAPI with k resolution by angle-resolved photoemission at 170 K. Our results show that the

spectral weight is strongly affected by the cubic symmetry although traces of the tetragonal band structure

are appreciated. Some deviations with respect to theoretical calculations are observed, which may help to

reach a more precise description of this paradigmatic system of the hybrid perovskite family. The project

leading to this application has received funding from the European Union’s Horizon 2020 research and

innovation programme under grant agreement No 687008 (GOTSolar).

1

Matière CondenséeCongrès général SFP 2017

Des oscillations de Shubnikov-de Haas particulières dans un métal organique à cônes de Dirac

Emilie Tisserond1, Miguel Monteverde1, Jean-Noël Fuchs1, Mark-Oliver Goerbig1, Pascale Auban-Senzier1, Claude Pasquier1 et Naoya Tajima2

1Laboratoire de Physique des Solides,UMR8502-CNRS, Université Paris-Sud, Orsay F-91405, France 2RIKEN,Hirosawa 2-1,Wako-shi, Saitama 351-0198, Japan

La plupart des matériaux étudiés par la physique de la matière condensée sont à base de fermions massifs vérifiant les relations de dispersion paraboliques usuelles. Or, depuis les années 2000, avec notamment l’obtention expérimentale du graphène, la physique de la matière condensée voit émerger de nouveaux matériaux, dont les relations de dispersion sont linéaires, mettant ainsi en évidence la présence de fermions de Dirac. C’est le cas du composé organique α-(BEDT-TTF)2I3(par la suite, dénoté αI3), sous forte pression hydrostatique (P>1,5GPa)1. Contrairement au cas du graphène purement bidimensionnel, la structure tridimensionnelle multi-couches du composé αI3 permet de sonder une physique beaucoup plus proche du point de Dirac. Cependant, la coexistencede fermions massifs et de fermions de Dirac au sein du composé αI3 rend cette physique particulièrement complexe, mais aussi riche et surprenante2.

Les oscillations de Shubnikov--de Haas (oscillations semi-classiques de la magnétorésistance) dans le αI3, sous fortes pressions et à de très basses températures (environ2 GPa et 200 mK),sont tout à fait inhabituelles et très particulières (voir figure). En effet, si le comportement périodique en 1/B de ces oscillations à bas champs magnétiques est bien connu et compris, il n’en est rien de la déviation à ce comportement qui apparaît à des champs plus élevés (~10T). Des résultats similaires mais moins prononcés ont été

observés récemment dans des échantillons de type isolants topologiques (voir encart figure)3.On interprète cette anomalie avec un modèle théorique original. 1N. Tajima et al., Journal of the Physical Society of Japan 75, 051010 (2006) 2M. Monteverdeet al., Physical Review B 87, 245110 (2013) 3A.R. Wright et al., Physical Review B 87 085411 (2013)

DMC: Division Matière Condensée Congrès général SFP 2017

Dynamic LDA for electronic excitations

Marco Vanzini1,2, Lucia Reining1,2, Matteo Gatti1,2,3

1 Laboratoire des Solides Irradiés, Ecole Polytechnique, CNRS, CEA, Université Paris-Saclay, 91128 Palaiseau, France 2 European Theoretical Spectroscopy Facility (ETSF) 3 Synchrotron SOLEIL, L'Orme des Merisiers, BP 48 Saint-Aubin, 91192 Gif sur Yvette, France

Density Functional Theory is an extremely useful tool for dealing with ground state properties such as the density or total energy. Kohn-Sham eigenvalues are often considered as approximated electronic excitations, but the resulting spectra are poor.

We propose a generalisation of the Kohn-Sham approach to address in an exact framework electron addition and removal spectra. They can be measured by photoemission experiments, and can be evaluated using a computationally expensive non-local Self Energy. Our method is instead based on a frequency-dependent local potential, which significantly reduces the computing time of 1

an ab-initio calculation.

To find this spectral potential in practice, we propose a jellium-based dynamical local density approximation (dynLDA): it relates the unknown potential to its homogeneous counterpart, via a non-trivial connector in space and frequency, which is based on physical insight.

In this poster, I will present the achievements and the limits of dynLDA, using models and real solids.

M. Gatti et al., Phys. Rev. Lett. 99, 057401 (2007)1

Congrès général SFP 2017 DMC

Signature(s) de la percolation en diffusion de la lumière

Jean-Christian Anglès d’Auriac et Pierre-Etienne Wolf i u i r i r A -CNRS, 25 Avenue des Martyrs, 38042 Grenoble, France

Lorsque la fraction p de sites choisis au hasard sur un réseau augmente, la taille du plus gros amas connexe diverge à une valeur pc. Ce phénomène de percolation, qui a de nombreuses manifestations naturelles et qui est un des exemples les plus simples de transition de phase, a été très étudié en physique statistique comme en mathématiques.

Figure : Facteur de structure pour la percolation sur un réseau carré LxL, L==16384, pour p=0.986 pc : orange : plus gros amas. Rouge : amas touchant les bords. Bleu et vert : fraction de germes aléatoires 10-4 et 10-5.

L’amas critique a une structure fractale de dimension fractale df , ce qui traduit l’invariance

d’échelle à pc. Le facteur de structure associé varie comme S(q) ~ q-df , une signature en principe

mesurable par une expérience de diffusion.

Cependant, au contraire par exemple de la résistivité électrique, la diffusion de rayonnement teste tous les amas, et pas uniquement le plus gros. Les inter-corrélations entre amas affectent ainsi le facteur de structure. A la limite où tous les amas sont retenus, le facteur de structure est celui d’une distribution aléatoire, constant en fonction de q. Le signal de diffusion dépend donc crucialement de l’existence d’un processus physique de sélection des amas sondés. Curieusement, ce problème n’a été que peu étudié. Nous avons réalisé des simulations numériques sur des échantillons de grande taille, à deux et trois dimensions, en ne sélectionnant que les amas contenant des germes donnés (« envahisseurs » dans le langage de la percolation d’invasion). Nos résultats permettent de décrire S(q) au-delà de la limite diluée (telle que la distance entre amas soit plus élevée que leur taille moyenne), et également de discuter le cas où seuls les amas touchant un bord sont sélectionnés. Nous illustrerons la pertinence de nos résultats dans le contexte de l’évaporation de l’hélium liquide confiné dans un milieu poreux aléatoire (Vycor) [1].

1. Bonnet, F., Melich, M., Puech, L., and Wolf, P. E. Light scattering study of collective effects during evaporation and condensation in a disordered porous material. EPL, 101(1):16010, 2013.

1

Congrès général SFP 2017

Structural Properties of the Aqueous Electrolyte LiCl6H2O at the Supercooled State using the (RMC) and (HRMC) simulations

M. Ziane1,2 , M. HABCHI2,3, S.M. Mesli2,3, F. Benzouine1, R. Benallal2,3 , A. Derouiche1,

M.Kotbi4

1 Polymer Physics and Critical Phenomena Laboratory; Faculty of Sciences Ben M'sik, Casablanca. , Morocco (e-

mail: zianesmp@gmail.com)

2 ISP group, NMSE division, URMER, Abou Bekr Belkaid University of Tlemcen, Algeria

3 Preparatory School in Sciences and Techniques, BP 165 RP, Bel Horizon, 13000 Tlemcen, Algeria. 4 Department of Physics, LPT, A.B. Belkaїd University, BP 119 Tlemcen, Algeria.

Abstract— This system possesses the property to become a glass through a metastable supercooled state when the temperature decreases. The three thermodynamic states of the LiCl6h2O were studied using the Reverse Monte Carlo (RMC) and the Hybrid Reverse Monte Carlo (HRMC) methods and many 3-dimensional atomic configurations have been created to simulate the structure of this aqueous electrolyte. RMC is based on partial correlation functions issue from neutron scattering. It computes radial distribution functions which allow exploring a number of structural features of the system. The results one obtains include some artifacts. To remedy for this, we use extension of the RMC algorithm, which introduces an energy penalty term into the acceptance criteria. This method is referred to as the Hybrid Reverse Monte Carlo (HRMC) method, Obtained results show a good matching between experimental and computed functions and a significant improvement in PDF's curves with potential constraint. It suggests a useful test of a defined interaction model for conventional simulation techniques.

Key words— RMC simulation, neutron scattering, Hybrid RMC simulation, Partial distribution function, Hydration shell, hydrogen bonds.

Division Matière Condensée (DMC) Congrès général SFP 2017

Structural, thermal and magnetic properties of Fe77Nb8B15 alloy

prepared by mechanical alloying

N. Bensebaa1, T. Chabi1, S. Alleg1, S. Azzaza1 and J.J. Sunol2

1 Laboratoire de Magnétisme et de Spectroscopie des solides, Département de Physique, Faculté des Sciences,

Université Badji Mokhtar B.P. 12, 23000 Annaba, Algérie. 2

Dep. De Fisica, Universitat de Girona, Campus Montilivi, Girona 17071, Spain.

Nanocrystalline alloy Fe77Nb8B15 was synthesized from elemental Fe, Nb and B powders in

a high energy planetary ball mill Retsch PM400, under argon atmosphere, using hardened steel

vials and balls. Structural, microstructural changes, magnetic properties and thermal stability of

the powders were followed by X-ray diffraction, magnetic measurements and differential scanning

calorimetry. After 50 h of milling, the Rietveld refinement of the X-ray diffraction patterns reveals

the formation of bcc Fe (Nb, B) solid solution, tetragonal Fe2B boride and amorphous type phase

in addition to the pure iron. The DSC scan shows the existence of several exothermic and

endothermic peaks related to the structural relaxation, recovery and grain growth. The

endothermic peaks at about 609°C can be attributed to the magnetic transition of Fe2B phase. The

coercivity, Hc, and the saturation magnetization, Ms, values are of about 83,9 Oe and 21,3 emu/g

respectively.

Keywords: Nanocrystalline materials; Mechanical alloying; FeNbB alloy; X-ray diffraction;

Differential scanning calorimetry; Vibrating sample magnetometer.