Probing valley phenomena with gate-defined valley splitters

TL;DR

This paper introduces a gate-defined valley splitter device in graphene multilayers that enables direct transport measurement of valley phenomena, providing new tools for probing valley polarization and order parameters.

Contribution

The paper proposes a novel gate-defined valley splitter device for graphene multilayers, enabling direct transport-based valley phenomena investigation and applications in quantum dot polarization and order parameter analysis.

Findings

Device works with robust magnetotransport response.

Resonant tunneling reveals valley polarization of quantum dot levels.

Combination of splitters resolves order parameter nature.

Abstract

Despite many reports of valley-related phenomena in graphene and its multilayers, current transport experiments cannot probe valley phenomena without the application of external fields. Here we propose a gate-defined valley splitter as a direct transport probe for valley phenomenon in graphene multilayers. First, we show how the device works, its magnetotransport response, and its robustness against fabrication errors. Secondly, we present two applications for valley splitters: (i) resonant tunneling of quantum dots probed by a valley splitter shows the valley polarization of dot levels; (ii) a combination of two valley splitters resolves the nature of order parameters in mesoscopic samples.