Non-Ohmic to Ohmic Crossover in the Breakdown of the Quantum Hall States in Graphene under Broadband Excitations
Phys. Rev. Lett. 137, 156602 – Published 9 October, 2026
DOI: https://doi.org/10.1103/5kkx-rcdh
Abstract
Graphene, through the coexistence of large cyclotron gaps and small spin and valley gaps, offers the possibility to study the breakdown of the quantum Hall effect (QHE) across a wide range of energy scales. In this Letter, we investigate the breakdown of the QHE in high-mobility graphene Corbino devices under broadband excitation ranging from dc up to 10 GHz. We find that the conductance is consistently described by variable range hopping (VRH) and extract the hopping energies from both temperature- and field-driven measurements. Using VRH thermometry, we can distinguish between non-Ohmic and Ohmic regimes of bulk conduction, which are dominated by electric-field-assisted VRH and Joule heating, respectively. Our results demonstrate that the breakdown in the quantum Hall regime of graphene is governed by a crossover from non-Ohmic, field-driven VRH to Ohmic, Joule-heating-dominated transport.
