Signatures of an intermediate 2d Coulomb phase at low temperatures

TL;DR

This paper investigates the low-temperature properties of a proposed intermediate Coulomb phase in 2D disordered fermion systems, revealing unique excitations that differ from known phases and vanish at high temperatures.

Contribution

It provides evidence for an intermediate 2D Coulomb phase with distinct excitations, expanding understanding of quantum phases in disordered fermion systems.

Findings

Existence of a new intermediate Coulomb phase.

Distinct low-energy excitations compared to Fermi glass and Wigner crystal.

Hexatic excitations disappear near the Fermi temperature.

Abstract

The study of the ground state of spinless fermions in 2d disordered clusters (Phys. Rev. Lett. {\bf 83}, 1826 (1999)) has suggested the existence of a new quantum phase for intermediate Coulomb energy to kinetic energy ratios $r_s$. Exact diagonalization of the same small clusters show that its low energy excitations (quantum ergodicity above a few ``hexatic'' excitations characterized by oriented currents) significantly differ from those occuring in the Fermi glass (weak $r_s$) and in the pinned Wigner crystal (large $r_s$). The ``hexatic'' excitations vanish for temperatures of order of the Fermi temperature.