• 文献标题:   Tunable valley Hall effect in gate-defined graphene superlattices
  • 文献类型:   Article
  • 作  者:   MARTINY JHJ, KAASBJERG K, JAUHO AP
  • 作者关键词:  
  • 出版物名称:   PHYSICAL REVIEW B
  • ISSN:   2469-9950 EI 2469-9969
  • 通讯作者地址:   Tech Univ Denmark
  • 被引频次:   0
  • DOI:   10.1103/PhysRevB.100.155414
  • 出版年:   2019

▎ 摘  要

We theoretically investigate gate-defined graphene superlattices with broken inversion symmetry as a platform for realizing tunable valley-dependent transport. Our analysis is motivated by recent experiments [C. Forsythe et al., Nat. Nanotechnol. 13, 566 (2018)] wherein gate-tunable superlattice potentials have been induced on graphene by nanostructuring a dielectric in the graphene/patterned-dielectric/gate structure. We demonstrate how the electronic tight-binding structure of the superlattice system resembles a gapped Dirac model with associated valley-dependent transport using an unfolding procedure. In this manner we obtain the valley Hall conductivities from the Berry curvature distribution in the superlattice Brillouin zone, and demonstrate the tunability of this conductivity by the superlattice potential. Finally, we calculate the valley Hall angle relating the transverse valley current and longitudinal charge current and demonstrate the robustness of the valley currents against irregularities in the patterned dielectric.