Incipient Formation of the Reentrant Insulating Phase in a Dilute 2D Hole System with Strong Interactions

TL;DR

This study investigates the transition between metallic and insulating phases in a dilute 2D hole system, revealing coexistence of phases and the influence of spin, advancing understanding of Wigner crystal formation.

Contribution

It provides new insights into the phase coexistence and the role of spin in the transition between metallic and insulating states in strongly interacting 2D systems.

Findings

Incipient RIP coexists with metallic phase at certain densities.

Temperature and magnetic field effects highlight phase competition.

Results support the Pomeranchuk effect in a mixed Wigner crystal and Fermi liquid.

Abstract

A new reentrant insulating phase (RIP) in low magnetic fields has been reported in the literature in strongly interacting 2D carrier systems and was suggested to be related to the formation of a Wigner crystal [e.g. Qiu et al, PRL 108, 106404 (2012)]. We have studied the transformation between the metallic liquid phase and the low field RIP in a dilute 2D hole system with large interaction parameter $r_s$ (~20-30) in GaAs quantum wells. Instead of a sharp transition, increasing density (or lowering $r_s$) drives the RIP into a state where an incipient RIP coexists with the metallic 2D hole liquid. The non-trivial temperature dependent resistivity and the in-plane magnetic field induced enhancement of the RIP highlight the competition between two phases and the essential role of spin in this mixture phase, and are consistent with the Pomeranchuk effect in a mixture of Wigner crystal and Fermi liquid.