Edge Dependence\nof Nonlocal Transport in Gapped Bilayer\nGraphene

The topological properties of gapped graphene have been\nexplored\nfor valleytronics applications. Prior transport experiments indicated\ntheir topological nature through large nonlocal resistance in Hall-bar\ndevices, but the origin of this resistance was unclear. This study\nfocused on dual-gate bilayer graphene (BLG) devices with naturally\ncleaved edges, examining how edge-etching with an oxygen plasma process\naffects electron transport. Before etching, local resistance at the\ncharge neutral point increased exponentially with the displacement\nfield and nonlocal resistance was well explained by ohmic contribution,\nwhich is typical of gapped BLG. After-etching, however, local resistance\nsaturated with increasing displacement field, and nonlocal resistance\ndeviated by 2 orders of magnitude from ohmic contribution. We suggest\nthat these significant changes in local and nonlocal resistance arise\nfrom the formation of edge conducting pathways after the edge-etching,\nrather than from a topological property of gapped BLG that has been\nclaimed in previous literatures.