Weak localisation, hole-hole interactions and the "metal"-insulator transition in two dimensions

TL;DR

This study investigates quantum effects in high-quality two-dimensional hole systems, revealing that weak localisation and hole-hole interactions persist in the metallic phase, suggesting no true metallic phase exists at zero temperature in two dimensions.

Contribution

It provides detailed experimental evidence that quantum corrections are present in 2D hole systems and challenges the existence of a true metallic phase at T=0.

Findings

Quantum corrections to resistivity are observed at low temperatures.

Weak localisation is evidenced by negative magnetoresistance.

No metallic phase exists at T=0 in two dimensions.

Abstract

A detailed investigation of the metallic behaviour in high quality GaAs-AlGaAs two dimensional hole systems reveals the presence of quantum corrections to the resistivity at low temperatures. Despite the low density ($r_{s}>10$) and high quality of these systems, both weak localisation (observed via negative magnetoresistance) and weak hole-hole interactions (giving a correction to the Hall constant) are present in the so-called metallic phase where the resistivity decreases with decreasing temperature. The results suggest that even at high $r_{s}$ there is no metallic phase at T=0 in two dimensions.