Strong Transport Anisotropy in a Ge/SiGe Quantum Well in Tilted Magnetic Fields

TL;DR

This study reveals a significant transport anisotropy in a Ge/SiGe quantum well's 2D hole gas, emerging only under combined perpendicular and in-plane magnetic fields, with potential implications for understanding quantum phases.

Contribution

It demonstrates a novel, highly tunable transport anisotropy in Ge/SiGe quantum wells induced by tilted magnetic fields, distinct from known nematic phases.

Findings

Resistance ratio exceeds 3×10^4 along different directions.

Anisotropy depends primarily on tilt angle.

Anisotropy persists at higher temperatures and filling factors.

Abstract

We report on a strong transport anisotropy in a 2D hole gas in a Ge/SiGe quantum well, which emerges only when both perpendicular and in-plane magnetic fields are present. The ratio of resistances, measured along and perpendicular to the in-plane field, can exceed $3\times 10^4$. The anisotropy occurs in a wide range of filling factors where it is determined {\em primarily} by the tilt angle. The lack of significant anisotropy without an in-plane field, easy tunability, and persistence to higher temperatures and filling factors set this anisotropy apart from nematic phases in GaAs/AlGaAs.