Neutral-current Hall effects in disordered graphene

TL;DR

This study demonstrates the detection of neutral-current Hall effects in disordered graphene, revealing valley currents with potential for room-temperature electronics, and explores how disorder and gate voltage influence these effects.

Contribution

It introduces a method to observe neutral-current Hall effects in disordered graphene and characterizes their dependence on disorder, gate voltage, and temperature.

Findings

Neutral-current Hall effect observed in graphene with disorder.

Neutral current relaxation length approximately 300 nm.

Effect persists with minimal temperature dependence from 7-300 K.

Abstract

A non-local Hall bar geometry is used to detect neutral-current Hall effects in graphene on silicon dioxide. Disorder is tuned by the addition of Au or Ir adatoms in ultra-high vacuum. A reproducible neutral-current Hall effect is found in both as-fabricated and adatom-decorated graphene. The Hall angle exhibits a complex but reproducible dependence on gate voltage and disorder, and notably breaks electron-hole symmetry. An exponential dependence on length between Hall and inverse-Hall probes indicates a neutral current relaxation length of approximately 300 nm. The short relaxation length and lack of precession in parallel magnetic field suggest that the neutral currents are valley currents. The near lack of temperature dependence from 7-300 K is unprecedented and promising for using controlled disorder for room temperature neutral-current electronics.