Phase diagram, correlation gap, and critical properties of the Coulomb glass

TL;DR

This study uses Monte Carlo simulations to explore the phase behavior and critical properties of the three-dimensional Coulomb glass model, revealing the absence of an equilibrium glass phase and characterizing the charge order transition.

Contribution

It provides the first detailed numerical analysis of the Coulomb glass phase diagram, confirming the universality class of the charge-order transition and validating the Efros-Shklovskii scaling near the Coulomb gap.

Findings

No evidence of an equilibrium glass phase down to low temperatures.

Charge-ordered phase exists at low disorder with a transition in the Random Field Ising universality class.

The density of states near the Coulomb gap follows Efros-Shklovskii scaling with   2.01  0.05.

Abstract

We investigate the lattice Coulomb glass model in three dimensions via Monte Carlo simulations. No evidence for an equilibrium glass phase is found down to very low temperatures, although the correlation length increases rapidly near T=0. A charge-ordered phase (COP) exists at low disorder. The transition to this phase is consistent with the Random Field Ising universality class, which shows that the interaction is effectively screened at moderate temperature. For large disorder, the single-particle density of states near the Coulomb gap satisfies the scaling relation g(e,T)=T^\delta f(|e|/T) with \delta = 2.01 +/- 0.05 in agreement with the prediction of Efros and Shklovskii. For decreasing disorder, a crossover to a larger effective exponent occurs due to the proximity of the COP.