Melting of the Electron Glass

A model of spinless interacting electrons in presence of randomness is examined using an extended dynamical mean-field formulation. When the interaction strength is large as 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 pseudo-gap in the single particle density of states, reminiscent of the Coulomb gap of Efros and Shklovskii. Due to 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.