University of Minnesota
School of Physics & Astronomy

Condensed Matter Seminar

Thursday, December 10th 2009
1:25 pm:
Condensed Matter Seminar in 210 Physics
Speaker: Matteo Palassini, University of Barcelona
Subject: Thermodynamics of the electron glass and the Coulomb gap

In disordered insulators, the interplay of the disorder and the long-range electron-electron interaction gives rise to a correlated regime at low temperature, the Coulomb glass or electron glass. The single-particle density of states exhibits a soft "Coulomb" gap, the shape of which is still debated and is reflected in the hopping conductivity. It was also predicted long ago that disordered insulators exhibit a "glassy" dynamics, which has now received ample experimental confirmation. In recent mean-field theoretical work, it was proposed that the glassy phenomenology reflects a transition to an equilibrium glass phase, similar to the much-debated Almeida-Thouless transition in spin glass. I will discuss the results of large-scale Monte Carlo simulations of the Coulomb glass addressing these questions. Our main results are a strong evidence against the existence of an equilibrium glass phase in 3D, and a confirmation of the Efros-Shklovskii prediction of a parabolic shape of the density of states at the Coulomb gap. I will also discuss results for the 3D Random Field Ising model that highlight the role of the interaction range, and for the 2D Coulomb glass.

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