Spin-valley 0.7 anomaly in bilayer graphene/WSe$_2$ quantum point contacts

TL;DR

This paper reports a clear 0.7 conductance anomaly in bilayer graphene/WSe$_2$ quantum point contacts, revealing the influence of spin-valley coupling and opening new avenues for valley physics research.

Contribution

It demonstrates the emergence of the 0.7 anomaly linked to spin-valley locked states in bilayer graphene, highlighting the role of valley degrees of freedom in quantum transport.

Findings

Observation of the 0.7 conductance anomaly at G=0.7×(2e^2/h)

Temperature and bias behavior similar to GaAs systems

Distinct magnetic field response confirming valley involvement

Abstract

We report a well-resolved 0.7 conductance anomaly at $G = 0.7\times(2e^2/h)$ in bilayer graphene/WSe$_2$ quantum point contacts. Proximity-enhanced spin-orbit coupling splits the four-fold ground state of bilayer graphene into well-separated spin-valley locked Kramers doublets. The anomaly emerges between these opposite spin-valley states. Despite fundamentally different band structure and wavefunction characteristics, the temperature and bias phenomenology closely mirror GaAs systems. In contrast, the parallel magnetic field response differs significantly, confirming the central role of valley degrees of freedom. This opens new pathways to study valley-exchange correlation physics in regimes inaccessible to conventional semiconductors.