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[PAST EVENT] Condensed Matter Seminar
May 4, 2015
3:30pm - 4:30pm
Abstract:
The main subject of this talk is thermal transport in the disordered Fermi and electron liquids at low temperatures. I plan to start with a brief introduction to the physics of quantum corrections to conductivity in disordered systems and the phenomenology of the metal-insulator transition in two-dimensional electron systems. Then, I will contrast approaches to the calculation of electric and thermal transport. A principle difficulty for the description of thermal transport is that temperature is an internal parameter, and a temperature gradient does not correspond to an external ?mechanical? force like a the one originating from an electric potential. We use Luttinger?s gravitational potentials as sources for finding the heat density and its correlation function. For a comprehensive study, we extend the RG analysis developed for electric transport by including the gravitational potentials into the RG scheme. The analysis reveals that for the disordered Fermi liquid the Wiedemann-Franz law remains valid even in the presence of quantum corrections caused by the interplay of diffusion modes and the electron-electron interaction. For the disordered electron liquid we additionally analyze inelastic processes induced by the Coulomb interaction at sub-temperature energies. While the general form of the correlation function has to be compatible with energy conservation, these inelastic processes are at the origin of logarithmic corrections violating the Wiedemann-Franz law.
The main subject of this talk is thermal transport in the disordered Fermi and electron liquids at low temperatures. I plan to start with a brief introduction to the physics of quantum corrections to conductivity in disordered systems and the phenomenology of the metal-insulator transition in two-dimensional electron systems. Then, I will contrast approaches to the calculation of electric and thermal transport. A principle difficulty for the description of thermal transport is that temperature is an internal parameter, and a temperature gradient does not correspond to an external ?mechanical? force like a the one originating from an electric potential. We use Luttinger?s gravitational potentials as sources for finding the heat density and its correlation function. For a comprehensive study, we extend the RG analysis developed for electric transport by including the gravitational potentials into the RG scheme. The analysis reveals that for the disordered Fermi liquid the Wiedemann-Franz law remains valid even in the presence of quantum corrections caused by the interplay of diffusion modes and the electron-electron interaction. For the disordered electron liquid we additionally analyze inelastic processes induced by the Coulomb interaction at sub-temperature energies. While the general form of the correlation function has to be compatible with energy conservation, these inelastic processes are at the origin of logarithmic corrections violating the Wiedemann-Franz law.