Signatures of sliding Wigner crystals in bilayer graphene at zero and finite magnetic fields

Abstract

Abstract AB-stacked bilayer graphene has emerged as a fascinating yet simple platform for exploring macroscopic quantum phenomena of correlated electrons. Under large electric displacement fields and near low-density van-Hove singularities, it exhibits a phase with features consistent with Wigner crystallization, including negative dR/dT and nonlinear bias behavior. However, direct evidence for the emergence of an electron crystal at zero magnetic field remains elusive. Here, we explore low-frequency noise consistent with depinning and sliding of a Wigner crystal or solid. At large magnetic fields, we observe enhanced noise at low bias current and a frequency-dependent response characteristic of depinning and sliding, consistent with earlier scanning tunnelling microscopy studies confirming Wigner crystallization in the fractional quantum Hall regime. At zero magnetic field, we detect pronounced AC noise whose peak frequency increases linearly with applied DC current—indicative of collective electron motion. These transport signatures pave the way toward confirming an anomalous Hall crystal.