Quantum Coulomb glass on the Bethe lattice

TL;DR

This paper investigates the quantum Coulomb glass on the Bethe lattice, revealing how strong interactions and disorder lead to a metallic glass phase with a pseudogap, and how quantum fluctuations melt this into a quantum liquid, with implications for Si inversion layers.

Contribution

It provides a comprehensive phase diagram of the quantum Coulomb glass on the Bethe lattice, combining diagrammatic perturbation theory and Monte Carlo simulations to characterize phases and fluctuations.

Findings

Identification of a metallic Coulomb glass phase with a pseudogap.

Quantum and thermal fluctuations melt the glass into a quantum liquid.

Density of states remains finite at the Fermi energy due to residual quantum fluctuations.

Abstract

We study the Coulomb glass emerging from the interplay of strong interactions and disorder in a model of spinless fermions on the Bethe lattice. In the infinite coordination number limit, strong interactions induce a metallic Coulomb glass phase with a pseudogap structure at the Fermi energy. Quantum and thermal fluctuations both melt this glass and induce a disordered quantum liquid phase. We combine self-consistent diagrammatic perturbation theory with continuous time quantum Monte-Carlo simulations to obtain the complete phase diagram of the electron glass, and to characterize its dynamical properties in the quantum liquid, as well as in the replica symmetry broken glassy phase. Tunneling spectra display an Efros-Shklovskii pseudogap upon decreasing temperatures, but the density of states remains finite at the Fermi energy due to residual quantum fluctuations. Our results bear relevance to the metallic glass phase observed in Si inversion layers.