Spintronic functionalities of magnetic topological insulators

The topological insulator is a newly found class of materials with an insulating bulk and conductive surface state. The surface state possesses Dirac dispersion with spin-momentum locking, that is, the electron spin is locked perpendicular to its momentum. Due to the characteristic band dispersion, the topological surface state has been demonstrated to exhibit quite a large spin Hall angle. As a result, the topological insulator yields versatile spintronic functionalities when it is combined with magnetism. To demonstrate various spintronic functionalities, we studied the transport properties of a magnetic-ion doped topological insulator, i.e., a magnetic topological insulator. In this article, we discuss current-induced magnetization switching due to the Edelstein effect and unidirectional magnetoresistance, or current-direction dependent magnetoresistance in a magnetic topological insulator. As an intriguing spintronic functionality specific to the magnetic topological insulator, the quantum anomalous Hall effect, i.e., a quantized version of the anomalous Hall effect, and the appearance of a chiral edge state at the domain wall are discussed. (author)