State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University , Beijing 100871, China.
School of Physics, Beijing Institute of Technology , Beijing 100081, China.
ACS Nano. 2017 Jun 27;11(6):6277-6285. doi: 10.1021/acsnano.7b02494. Epub 2017 May 16.
It has been theoretically proposed that the spin textures of surface states in a topological insulator can be directly transferred to graphene by means of the proximity effect, which is very important for realizing a two-dimensional topological insulator based on graphene. Here we report the anomalous magnetotransport properties of graphene-topological insulator BiSe heterojunctions, which are sensitive to the electronic coupling between graphene and the topological surface state. The coupling between the p orbitals of graphene and the p orbitals of the surface states on the BiSe bottom surface can be enhanced by applying a perpendicular negative magnetic field, resulting in a giant negative magnetoresistance at the Dirac point up to about -91%. An obvious resistance dip in the transfer curve at the Dirac point is also observed in the hybrid devices, which is consistent with theoretical predictions of the distorted Dirac bands with nontrivial spin textures inherited from the BiSe surface states.
理论上提出，通过近邻效应，拓扑绝缘体表面态的自旋纹理可以直接转移到石墨烯上，这对于实现基于石墨烯的二维拓扑绝缘体非常重要。在这里，我们报告了石墨烯-拓扑绝缘体 BiSe 异质结的反常磁输运性质，该性质对石墨烯与拓扑表面态之间的电子耦合非常敏感。通过施加垂直的负磁场，可以增强石墨烯的 p 轨道与 BiSe 下表面的表面态的 p 轨道之间的耦合，从而在狄拉克点处产生高达约-91%的巨大负磁阻。在混合器件中，在狄拉克点处的转移曲线中也观察到明显的电阻下降，这与具有拓扑表面态所继承的非平凡自旋纹理的扭曲狄拉克能带的理论预测一致。
