| 研究実績の概要 |
This year research was focused on the study of one of the key properties of Topological Insulators (TI) - the spin-momentum locking of surface Dirac electrons. This property has been tested by measuring the anisotropy of the magnetoresistance in our MBE-grown (Bi1-xSbx)2Te3 thin films under the rotation of the in-plane magnetic field. Using the developed last year comprehensive method for fabricating dual-gated devices, we were able to control the concentration and the type of charge carries on the top and bottom surfaces independently. Measuring the angular dependence of the resistance in the constant magnetic field which is rotated in the plane of the sample, we found a clear anisotropic magneto-resistance (AMR) and a planar Hall effect (PHE) in our films. It has been known for decades that such AMR and PHE can be realized in ferromagnetic materials, but it is completely unexpected in non-magnetic TI films. Moreover, the amplitude of MR anisotropy and PHE can be effectively controlled by electrostatic gating. This observation might be related to the unique spin-momentum locking in TIs.
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