Proceedings PaperSpin-orbit torque-induced magnetization reversal in topological insulator/magnetic insulator bi-layered structures (Conference Presentation)
Due to the spin-momentum locking of their topological surface states (TSS), topological insulators are expected to host spin-orbit coupling that is considerably stronger than in heavy metals. Such spin-orbit coupling can give rise to a strong spin-orbit torque that can switch a neighboring ferromagnet. This effect may be absent if the ferromagnet is electrically conductive because it can completely suppress the TSS, but it should be present if the ferromagnet is insulating. This talk reports TSS-induced switching in a bi-layered structure consisting of a topological insulator Bi2Se3 and an insulating ferromagnet BaFe12O19. A charge current in Bi2Se3 can switch the magnetization in BaFe12O19 up and down. When the magnetization is switched by a field, a current in Bi2Se3 can reduce the switching field by about 4000 Oe. The switching efficiency at 3 K is 300 times higher than at room temperature; it is about 30 times higher than in Pt/BaFe12O19 structures. Such strong effects originate from the presence of more pronounced TSS at low temperatures due to enhanced surface conductivity and reduced bulk conductivity.