Melting of the electron glass

A model of spinless interacting electrons in the presence of disorder is examined using an extended dynamical mean-field formulation. When the interaction strength is large compared to the Fermi energy, a low temperature glassy phase is identified, which in our formulation corresponds to a replica symmetry breaking instability. The glassy phase is characterized by a pseudogap in the single-particle density of states, reminiscent of the Coulomb gap of Efros and Shklovskii. Because of ergodicity breaking, the "zero-field-cooled" compressibility of this electron glass vanishes at T = 0, consistent with absence of screening. When the Fermi energy exceeds a critical value, the glassy phase is suppressed, and normal metallic behavior is recovered.