Topological valley transport at the curved boundary of a folded bilayer graphene

摘要: The development of valleytronics demands long-range electronic transport with preserved valley index, a degree freedom similar to electron spin. A promising structure for this end is topological one-dimensional channel formed in bilayer graphene, called domain wall. In these channels, the valley-index defines propagation direction charge carriers, and chiral edge states are robust over many kinds disorder. However, fabrication walls challenging, requiring design complex multi-gate structures or production on rough substrates, showing limited mean free path. Here, we report high-quality wall at curved boundary folded graphene. Our experiments reveal ballistic such channels two-terminal resistance close R = e2/4h zero-magnetic field four-terminal near zero. At bulk, measure tunable band gap.