Anisotropic magnetoresistance in topological insulator   Bi1.5Sb0.5Te1.8Se1.2/CoFe heterostructures
  Topological insulator is composed of an insulating bulk state and time reversal symmetry protected two-dimensional surface states. One of the characteristics of the surface states is the locking between electron momentum and spin orientation. Here, we report a novel in-plane anisotropic magnetoresistance in topological insulator Bi1.5Sb0.5Te1.8Se1.2/CoFe heterostructures. To explain the novel effect, we propose that the Bi1.5Sb0.5Te1.8Se1.2/CoFe heterostructure forms a spin-valve or Giant magnetoresistance device due to spin-momentum locking. The novel in-plane anisotropic magnetoresistance can be explained as a Giant magnetoresistance effect of the Bi1.5Sb0.5Te1.8Se1.2/CoFe heterostructures. 
B. Xia, P. Ren, Azat Sulaev, Z.P. Li, P. Liu, Z.L. Dong, and L. Wang
cond-mat.mes-hall