Topological Spintronics and Majorana Fermions

摘要

Spin-orbit interaction has offered a versatile platform in the study of novel physical phenomena in condensed matters.It enables charge-to-spin conversion for implementing functional spintronic devices, and can even change the bandtopology when it is strong enough, giving rise to exotic quantum states of matters such as topological insulators (TIs).Here, we demonstrate functional topological spintronic devices employing multiple TI-based material structures. First, weachieved current-driven magnetization switching in TI/ferrimagnet heterostructures at room temperature. A low switchingcurrent density and a fast switching speed is demonstrated in this system, due to the highly efficient topological surfacestates and the fast spin dynamics near compensation point in ferrimagnets. Besides, the magnetization switching can beeven realized without the assist of external magnetic field in a magnetic TI/antiferromagnet system, making it a promisingcandidate for applicable spintronic memory devices. Finally, when interfacing a quantum anomalous Hall insulator TI withNb, an s-wave superconductor, the signature of chiral Majorana edge modes is observed as the half-quantized plateaus ofe2/2h in conductivity. The experimental evidence of Majorana Fermions holds promise for error-tolerant topologicalquantum computation robust against external local perturbations.