Quantum and frustration effects on fluctuations of the inverse compressibility in two-dimensional Coulomb glasses

TL;DR

This study investigates how electron-electron interactions, disorder, magnetic fields, and frustration influence fluctuations in the inverse compressibility of two-dimensional Coulomb glasses, revealing unique distribution patterns and localization effects.

Contribution

It provides a systematic analysis of the combined effects of interactions, disorder, magnetic field, and frustration on inverse compressibility fluctuations in 2D Coulomb glasses, highlighting new distribution behaviors.

Findings

Unusual right-biased inverse compressibility distribution in clean, strongly interacting samples.

Weak magnetic fields generally suppress fluctuations, but can increase them in clean, weakly interacting samples.

Frustration enhances electron localization and fluctuations, while strong frustration suppresses interaction effects.

Abstract

We consider interacting electrons in a two-dimensional quantum Coulomb glass and investigate by means of the Hartree-Fock approximation the combined effects of the electron-electron interaction and the transverse magnetic field on fluctuations of the inverse compressibility. Preceding systematic study of the system in the absence of the magnetic field identifies the source of the fluctuations, interplay of disorder and interaction, and effects of hopping. Revealed in sufficiently clean samples with strong interactions is an unusual right-biased distribution of the inverse compressibility, which is neither of the Gaussian nor of the Wigner-Dyson type. While in most cases weak magnetic fields tend to suppress fluctuations, in relatively clean samples with weak interactions fluctuations are found to grow with the magnetic field. This is attributed to the localization properties of the electron states, which may be measured by the participation ratio and the inverse participation number. It is also observed that at the frustration where the Fermi level is degenerate, localization or modulation of electrons is enhanced, raising fluctuations. Strong frustration in general suppresses effects of the interaction on the inverse compressibility and on the configuration of electrons.