トポロジカル絶縁体の界面効果

抄録

We study charge transport on the surface state of topological insulator where two-dimensional Dirac electron is generated. We put ferromagnetic insulator or superconductor on the topological insulator and reveal anomalous charge transport on the surface. We first consider the charge transport through a ferromagnetic insulator/ferromagnetic insulator (FI/FI) junction on a topological insulator. The resulting conductance across the interface depends sensitively on the directions of the magnetizations of the two FI, showing anomalous behaviors compared with the conventional spin valve. It is found that the conductance depends strongly on the in-plane direction of the magnetization. Moreover, in sharp contrast to the conventional magnetoresistance effect, the conductance at the parallel configuration can be much smaller than that at the antiparallel configuration. We also study the transport properties of a normal metal (N)/FI/superconductor (S) junction formed on the surface of a three-dimensional topological insulator, where chiral Majorana edge mode exists at the FI/S interface. We find that the chiral Majorana edge mode generated in N/FI/S junction strongly influences the charge conductance.