Takagaki Y
Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e. V., Hausvogteiplatz 5-7, 10117 Berlin, Germany.
J Phys Condens Matter. 2021 May 27;33(25). doi: 10.1088/1361-648X/abf8d1.
Magnetotransport properties of zigzag and armchair graphene nanoribbons that are in contact with superconductors are investigated using a tight-binding model. The cyclotron orbital motion together with the quantum interference under the coexistence of Andreev and normal reflections gives rise to a number of oscillations in characteristic magnetic-field regimes when the superconducting coupling is weak. The oscillations become irregular and/or suppressed as the coupling is made strong. The period of the oscillations differs from that when a nonrelativistic two-dimensional electron gas is employed rather than the graphene sheet. The modifications of the oscillations are attributed to the phase shift associated with the reflection from the graphene-superconductor interface. The presence of a magnetic field suppresses the quantum blocking of Andreev transmission, which occurs for the edge mode of zigzag nanoribbons, in the same way regardless of it being induced by the Andreev retro- or specular reflection.
利用紧束缚模型研究了与超导体接触的锯齿形和扶手椅形石墨烯纳米带的磁输运性质。当超导耦合较弱时，在安德列夫反射和正常反射共存的情况下，回旋轨道运动与量子干涉会在特征磁场区域产生许多振荡。随着耦合变强，振荡变得不规则和/或受到抑制。振荡周期与使用非相对论二维电子气而非石墨烯片时不同。振荡的变化归因于与石墨烯 - 超导体界面反射相关的相移。磁场的存在抑制了锯齿形纳米带边缘模式发生的安德列夫传输的量子阻塞，无论这种阻塞是由安德列夫逆反射还是镜面反射引起的，其抑制方式都是相同的。
