Valley-momentum locking in a graphene superlattice with Y-shaped Kekulé bond texture

Abstract

Recent experiments by Gutiérrez $\text{et al.}$ [Nature Phys. $\text{12}$, 950 (2016)] on a graphene-copper superlattice have revealed an unusual Kekulé bond texture in the honeycomb lattice --- a Y-shaped modulation of weak and strong bonds with a wave vector connecting two Dirac points. We show that this so-called "Kek-Y" texture produces two species of massless Dirac fermions, with valley isospin locked parallel or antiparallel to the direction of motion. In a magnetic field $B$ the valley degeneracy of the $B$-dependent Landau levels is removed by the valley-momentum locking --- but a $B$-independent and valley-degenerate zero-mode remains.

Updated verstion; 9 pages, 6 figures

References in corpus (8)

• The electronic properties of graphene
• Andreev reflection and Klein tunneling in graphene
• Spin qubits in graphene quantum dots
• Electron fractionalization in two-dimensional graphenelike structures
• Single-Valley Engineering in Graphene Superlattices
• Zero-energy states in corrugated bilayer graphene
• Kekule' textures, pseudo-spin one Dirac cones and quadratic band crossings in a graphene-hexagonal indium chalcogenide bilayer
• Heavy going

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