In gapped Dirac materials, the topological current associated with each valley can flow in opposite directions creating long-range charge-neutral valley currents. We report valley currents in hBN/bilayer-graphene heterostructures with an energy gap, which is tunable by a perpendicular electric (displacement) field in a dual-gated structure. We observed significant nonlocal resistance, consistent with the scaling theory of the valley Hall effect. In the low-temperature limit, the nonlocal resistance approaches a saturated value near the "quantum limit," indicating the emergence of quantum valley currents.
@article{arxiv.2410.05636,
title = {Gapped Dirac materials and quantum valley currents in dual-gated hBN/bilayer-graphene heterostructures},
author = {Takuya Iwasaki and Yoshifumi Morita and Kenji Watanabe and Takashi Taniguchi},
journal= {arXiv preprint arXiv:2410.05636},
year = {2024}
}