Wigner crystallization and metal-insulator transition of two-dimensional holes in GaAs/AlGaAs at B=0

TL;DR

This study investigates the transport properties of ultra-clean two-dimensional holes in GaAs/AlGaAs, revealing a metal-insulator transition at a critical interaction parameter consistent with Wigner crystallization predictions.

Contribution

It provides experimental evidence linking the metal-insulator transition in 2D holes to Wigner crystallization at a specific interaction strength.

Findings

Metal-insulator transition occurs at r_s=35.1±0.9

Transition point aligns with theoretical Wigner crystallization predictions

High mobility and low disorder enable precise transition measurement

Abstract

We report the transport properties of a low disorder two-dimensional hole system (2DHS) in the GaAs/AlGaAs heterostructure, which has an unprecedentedly high peak mobility of $7\times 10^5cm^2/Vs$, with hole density of $4.8\times 10^9 cm^{-2}<p<3.72\times 10^{10}cm^{-2}$ in the temperature range of $50mK<T<1.3K$. From their T, p, and electric field dependences, we find that the metal-insulator transition in zero magnetic field in this exceptionally clean 2DHS occurs at $r_s=35.1\pm0.9$, which is in good agreement with the critical $r_s$ for Wigner crystallization ${r_s}^c=37\pm 5$, predicted by Tanatar and Ceperley for an ideally clean 2D system.