Thermopower of Interacting GaAs Bilayer Hole Systems in the Reentrant Insulating Phase near $\nu=1$

TL;DR

This study investigates thermopower in interacting GaAs bilayer hole systems, revealing a divergence at low temperatures in the insulating phase indicative of a pinned Wigner solid formation near the quantum Hall state at =1.

Contribution

It provides the first thermopower measurements of bilayer hole systems showing evidence of a Wigner solid near =1, including an energy gap and phase diagram.

Findings

Thermopower diverges as temperature decreases in the insulating phase.

Evidence of an energy gap consistent with Wigner solid formation.

Constructed a melting phase diagram for the Wigner solid.

Abstract

We report thermopower measurements of interacting GaAs bilayer hole systems. When the carrier densities in the two layers are equal, these systems exhibit a reentrant insulating phase near the quantum Hall state at total filling factor $\nu=1$. Our data show that as the temperature is decreased, the thermopower diverges in the insulating phase. This behavior indicates the opening of an energy gap at low temperature, consistent with the formation of a pinned Wigner solid. We extract an energy gap and a Wigner solid melting phase diagram.