Direct observation of proximity-induced magnetism and spin reorientation in topological insulator on a ferrimagnetic oxide
Journal
Applied Physics Letters
Journal Volume
114
Journal Issue
8
Date Issued
2019
Author(s)
Yang, C.-Y.
Lee, Y.-H.
Ou Yang, K.-H.
Chiu, K.-C.
Tang, C.
Liu, Y.
Zhao, Y.-F.
Chang, C.-Z.
Chang, F.-H.
Lin, H.-J.
Shi, J.
Abstract
The quantum anomalous Hall effect (QAHE) in a magnetic topological insulator system without the need of an external magnetic field becomes of great interest because of its dissipationless spin currents. The proximity effect via a magnetic adlayer is a promising strategy to bring magnetism into a topological insulator (TI) due to its boosted Curie temperature for a realistic application. In this work, a proximity-induced magnetism above 90 K in a TI, (Bi0.25Sb0.75)2Te3, on a ferrimagnetic adlayer with perpendicular magnetic anisotropy, thulium-iron-garnet (TIG), was evidenced directly by using magnetic circular dichroism. A competition between exchange couplings with different sublattice-sites was further revealed element-specifically in a temperature-driven spin-reorientation of TI, bringing an issue on magnetic inhomogeneity at the interface, which might cause difficulties in obtaining QAHE in such a TI/TIG bilayer system. Our results prove directly the robust magnetism of TI above liquid nitrogen temperatures and also give a deep insight into the mechanism of interfacial coupling in the proximity effect for the bilayer of TI and magnetic oxide, which could be essential for the design of a system with QAHE.
Type
journal article