Symmetry Breaking of the Persistent Spin Helix in Quantum Transport

TL;DR

This paper derives a new formula for weak localization magnetoconductivity in quantum transport, exploiting symmetry in spin states, and confirms it through experiments in GaAs quantum wells, advancing spin-orbit coupling understanding.

Contribution

It introduces a closed-form expression for magnetoconductivity considering symmetry breaking, validated by experiments, enhancing the theoretical framework of spin-orbit interactions in quantum transport.

Findings

Excellent agreement between theory and experiment.

Reliable parameter extraction method developed.

Experimental confirmation of the new theoretical model.

Abstract

We exploit the high-symmetry spin state obtained for equal Rashba and linear Dresselhaus interactions to derive a closed-form expression for the weak localization magnetoconductivity -- the paradigmatic signature of spin-orbit coupling in quantum transport. The small parameter of the theory is the deviation from the symmetry state introduced by the mismatch of the linear terms and by the cubic Dresselhaus term. In this regime, we perform quantum transport experiments in GaAs quantum wells. Top and back gates allow independent tuning of the Rashba and Dresselhaus terms in order to explore the broken-symmetry regime where the formula applies. We present a reliable two-step method to extract all parameters from fits to the new expression, obtaining excellent agreement with recent experiments. This provides experimental confirmation of the new theory, and advances spin-orbit coupling towards a powerful resource in emerging quantum technologies.