Séminaires Nanoélectronique Quantique

Retrouver tous les "Séminaires Nanoélectronique Quantique" passés et à venir dans cette rubrique.

Le prochain séminaire aura lieu le :
Mardi 11 juillet 2017 à 14h
Salle Rémy Lemaire - Institut Néel
Inscription obligatoire

Shaffique Adam (National University of Singapore)
The role of electron-electron interactions in graphene

About ten years ago, a new electronic material appeared – notable not only for its ease of preparation and theoretical simplicity, but also by its promise for future electronic devices. Single monatomic sheets of carbon, known as graphene, are described as weakly interacting massless Dirac fermions and in many ways, are a textbook system to test physical models. In this talk, I will begin by briefly reviewing the theory for graphene at the Dirac point where competing effects of disorder, electron-electron interactions, and quantum interference conspire together to give a surprisingly robust state whose properties can be described using a weakly-interacting semi-classical picture [1]. Motivated by some recent experiments in ultra-clean graphene, we use a combination of nonperturbative numerical and analytical techniques that incorporate both the contact and long-range parts of the Coulomb interaction to address the role of electron-electron interactions at the Dirac point in the absence of disorder. We show that without strain, graphene remains metallic. But that a rather large – but experimentally realistic – uniform and isotropic strain provides a promising route to make graphene an antiferromagnetic Mott insulator [2]. Finally, we address the interaction enhancement of the Fermi velocity. Using quantum Monte-Carlo simulations with a long-range Coulomb tail, we identify the two previously discussed regimes : a Gross-Neveu transition to a strongly correlated Mott insulator, and a semi-metallic state with a logarithmically diverging Fermi velocity accurately described by the random phase approximation. Most interestingly, experimental realizations of Dirac fermions span the crossover between these two regimes providing the physical mechanism that masks this velocity divergence. We explain several long-standing mysteries including why the observed Fermi velocity in graphene is consistently about 20 percent larger than the best values calculated using ab initio and why graphene on different substrates show different behavior [3].

[1] S. Das Sarma, S. Adam, E. H. Hwang, and E. Rossi, “Electronic transport in two dimensional graphene”, Rev. Mod. Phys. 83, 407 (2011).

[2] H. Tang, E. Laksono, J.N.B. Rodrigues, P. Sengupta, F.F. Assaad, and S. Adam, "Interaction driven metal-insulator transition in strained graphene", Phys. Rev. Lett. 115, 186602 (2015) ;

[3] H. Tang, J.N. Leaw, J.N.B. Rodrigues, I. F. Herbut, P. Sengupta, F.F. Assaad, and S. Adam, "The role of electron-electron interactions in graphene", Submitted (2017).

Contact : Shaffique Adam

Les Organisateurs.
M. Hocevar, B. Sacepe, R. Whitney, C. Groth

Si vous souhaitez planifier des invitations, merci de nous contacter à l’adresse suivante :

A venir

20 juin 2017
Charge quantum interference device on superconducting nano-wires de Oleg Astafiev (Royal Holloway, University of London)
13 juin2017
Evolving functionality in nanomaterial networks de Wilfred G. van der Wiel (University of Twente, The Netherlands)
6 juin2017
Relaxation of an Electron Spin in a Moving Quantum Dotby Xuedong Hu (Department of Physics, University at Buffalo, USA)
30 mai
Understanding and exploiting interactions between components in quantum circuits de Philippe Joyez (SPEC, CEA-Saclay)
22 mai 2017
Feedback-tuned high fidelity gates for (GaAs based) two-electron spin qubits
de Hendrik Bluhm (RWTH Aachen University, Allemagne)

16 mai 2017
Electron teleportation in multi-terminal Majorana islands : Kondo effect at high temperature de Karen Michaeli (Weizmann Institute for Science, Israel)
9 mai 2017
Superconducting Atom Chips de Rainer Dumke (Nanyang Technological University, Singapore)

4 mai 2017
Quantum Physics in One Dimension using Nanostructured Josephson-junction Arrays de Tim Duty (University of New South Wales, Sydney)

20 avril 2017
Les bits quantiques MOS de Prof. Michel Pioro-Ladrière (Professeur associé, Département de physique, Université de Sherbrooke et Directeur adjoint, Institut Quantique, Université de Sherbrooke)
11 avril 2017
Quantum microwave devices based on inelastic Cooper pair tunneling de Max Hofheinz (CEA INAC)

28 mars 2017
Spin to charge conversion at room temperature using spin orbit coupling and recently discovered topological insulators de Laurent Vila (SPINTEC)

21 mars 2017

Spin Dynamics in Out-of-Equilibrium Superconductors de Charis Quay (Laboratoires de Physique des Solides, Université Paris Sud)

14 février 2017
Quantized circular photogalvanic effect in Weyl semimetals de Adolfo Grushin (Department of Physics, UC Berkeley et Institut Néel, CNRS & UGA)

7 février 2017
Confining the state of light to a quantum manifold by engineered two-photon loss de Zaki Leghtas (Laboratoire Pierre Aigrain - Ecole Normale Supérieure)

31 janvier 2017
Many-Body Localization Basics - Recent Highlights - Experimental possibilities de Nicolas Laflorencie (Laboratoire de Physique Théorique, Toulouse)

24 janvier 2017
Fluctuation theorems in engineered environments de Marcelo F. Santos (Universidade Federal do Rio de Janeiro, Brésil)

17 janvier 2017
THz Spectroscopy on Disordered Superconductors and the “Superconducting Dome” of Granular Aluminum de Marc Scheffler (Physikalisches Institut, University of Stuttgart, Germany)

10 janvier 2017
Mesoscopic Spectroscopy with Josephson Junctions de Caglar GIRIT (Collège de France, Paris)

13 décembre 2016
Ultrastrong light-matter with propagating photons de Juan José García Ripoll (Institute of Fundamental Physics, Spain)

10 novembre 2016
Exciton states mixing and second harmonics generation in transition metal dichalcogenide monolayers de Mikhail Glazov (Ioffe Institute, Russie)

11 octobre 2016
Quantum Phase Slips and Voltage Fluctuations de Andrei D. Zaikin (Karlsruhe Institute of Technology (KIT), Germany)

4 octobre 2016
2D solids : optical spectroscopies and nano-optomechanics de Antoine Reserbat-Plantey (ICFO Barcelone)




août 2017 :

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juillet 2017 | septembre 2017