CMSP seminars coming up tomorrow and thursday

[Cond.Matt. & Stat.Mech.Section]

JOINT ICTP/SISSA STATISTICAL PHYSICS SEMINAR

 
 
Tuesday, 28 May   -   11:30 a.m.

 

Giambiagi Lecture Hall, Adriatico Guesthouse - lower level

 

Silvio FRANZ   ( LPTMS - Orsay )

 


"Boltzmann pseudodynamics for  spin glasses and liquids"



Abstract

 
More than 10 years ago, it was realized that mean field glassy dynamics, with the emergence of aging and effective temperatures, can be understood as quasi-equilibrium exploration of configuration space. The formalization of this notion, only recently proposed, defines a Markov chain where short times are coarse grained, and subsequent configurations are chosen according to a constrained Boltzmann distribution.

In mean field spin glasses, this pseudodynamic rule admits, in the long time limit, a description leading to glassy solutions identical to the ones corresponding to real (Langevin) dynamics. The treatment of the pseudodynamics through replicas unveils a longly suspected relation between replicas and the supersymmetry of the Langevin equation.

The application of the formalism to liquids avoids the difficulties related to short time conservation laws, and allows to use equilibrium approximation schemes of liquid theory to study long time dynamics. The scheme is applied to a closure scheme of hierarchical equations recently proposed by Szamel and to liquids in the hypernetted chain (HNC) approximation. It is shown that the former case leads to the standard Mode Coupling Theory (MCT) equations of Gœtze, thus giving an interpretation of it. The second case also gives rise to MCT-like equations, but in a framework where, differently from MCT that requires the input of equilibrium structure factors, static equilibrium and dynamical quantities are computed in a unified consistent framework.

Refs. SF and G. Parisi, JSTAT P02003 (2013), SF, G. Parisi and P. Urbani, arXiv:1212.4291



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SEMINAR on    Disorder and strong electron correlations
 


Thursday, 30 May  -  11:30 a.m.

 

Luigi Stasi Seminar Room,  Leonardo Building - first floor

 

Michael SCHUETT    (Karlsruhe Institute of Technology)

 


"Hall-drag and magneto-drag in  graphene via kinetic equation approach"

 

Abstract

 
Recently, Coulomb drag measurements have been performed in graphene, usually in the presence of magnetic fields as well.  In this work we calculate the magneto-drag and the Hall-drag resistivity at finite temperature for two graphene monolayers by solving the quantum kinetic equation.  The presented theory is valid in the hydrodynamic regime, which is dominated by inelastic scattering. The microscopic formulation supports a phenomenological Drude-like picture which for large concentrations equals the usual Drude form, and for small concentration an effective two-band-Drude equation.  Our theory allows for a qualitative description for arbitrary chemical potentials.  An emphasis is put on the Hall-drag which is absent when derived from the standard Drude equation.  We show that the Hall-drag vanishes along the line of opposite carrier concentration in the layers, but we also identify non trivial concentrations at which the Hall-drag vanishes.