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Archives - Séminaires 2012

1.2. Séminaires 2012

Séminaires 2012 18/12/2012 P.D. Grigoriev, L.D. Landau Institute for Theoretical Physics RAS, 142432, Chernogolovka, Russia "Monotonic growth and other new features of interlayer magnetoresistance in strongly anisotropic quasi-2D compounds" Abstract 11/12/2012 Stevan Arsenijevic, LNCMI "Thermopower as a fingerprint of quantum criticality" 4/12/2012 Cécile Daversin, LNCMI "High field (...)

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Terahertz time-domain magneto-spectroscopy

6/03/2012 Jean Léotin, LNCMI-Toulouse A revival of THz magneto-spectroscopy is nowadays taking place with implementation of simple and reliable time-domain spectrometers based on novel femtosecond lasers. One basic advantage of time-domain spectroscopy (TDS) is simultaneous measurement of amplitude and phase spectra of the THz electric field. Moreover, the measurement is ultrafast, coherent, covers a wide spectral range, typically from 0.1 to 5THz, and can ultimately display signal to noise (...)

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Magnetism and Superconductivity in the Iron-based Superconductor La1-xFxFeAs as Probed by Nuclear Magnetic Resonance

13/03/2012 Franziska Hammerath, IFW, Dresden, Germany In my talk I will give an overview of NMR measurements on LaO1-xFxFeAs with 0 ≤ x ≤ 0:1, covering a broad range of the phase diagram from magnetically-ordered to optimally-doped superconducting samples [1]. Considering the normal state properties, I will mainly focus on the role of spin fluctuations in pnictides. For underdoped superconducting samples (x = 0.045, x = 0.05 and x = 0.075) the 75As NMR spin-lattice relaxation rate (...)

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Shot-noise measurements in graphene

15/03/2012 Mickaël Fay, IN, Grenoble, France In this talk, I will first give a general introduction to shot-noise which originates from the discrete nature of charge carriers in mesoscopic devices. Shot-noise gives information on the electronic transport that can not be obtained by simple conductance measurements, such as the effective charge of the carriers. Moreover, shot-noise can be used to probe the electronic temperature of mesoscopic systems and it is even possible to use this effect (...)

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Mise en forme et caractérisation de matériaux aux propriétés physiques utiles pour des applications

22/03/2012 Yohan Thimont, CRISMAT, UMR 6508, Caen, France Au cours de ce séminaire, les propriétés de supraconduction et de conducteurs transparents pour des applications magnétique, optiques, et de transport seront essentiellement ciblés. Nous nous pencherons sur la problématique de leurs mise en formes par différents moyens techniques comme, le dépôt de couche minces par ablation laser pulsé ou encore le spark plasma sintering puis à la compréhension des phénomènes physiques mis en jeux à partir (...)

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Une approche optique de l’intrication entre le magnétisme et la ferroélectricité dans les multiferroïques

4/05/2012 Pauline Rovillain, School of Physics University of New South Wales, Sydney, Australia Nous montrons ici une étude par spectroscopie Raman du couplage magnétoélectrique dans les deux familles de multiferroïques à travers BiFeO3 (type I) où les ordres magnétique et ferroélectrique coexistent et TbMnO3 (type II) où la ferroélectricité est induite par la structure de spin. Dans BiFeO3, la coexistence et l’interaction des ordres offrent l’opportunité de contrôler les spins via un champ électrique. (...)

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The Superconducting Proximity Effect through graphene from zero field to the Quantum Hall regime

15/05/2012 Sophie Guéron, LPS, Orsay, France The celebrated electronic band structure of graphene leads to many interesting features. Among them is the possibility to tune its carrier density from electron to hole, with the consequence that the Integer Quantum Hall effect is observed over a wide range of magnetic fields. Another consequence is the fact that transport can proceed via carriers of either the conduction or the valence band, depending on the doping, and may even proceed via a (...)

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Monotonic growth and other new features of interlayer magnetoresistance in strongly anisotropic quasi-2D compounds

18/12/2012 P.D. Grigoriev, L.D. Landau Institute for Theoretical Physics RAS, 142432, Chernogolovka, Russia Interlayer magnetoresistance in strongly anisotropic quasi-2D metals, where the interlayer hopping time is comparable to the cyclotron period, has many qualitatively new features. This makes the standard 3D theory inapplicable to these compounds. In my talk I briefly summarize the old results and introduce the recent theoretical (...)

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