Proximity-Induced Magnetic Order in a Transferred Topological Insulator Thin Film on a Magnetic Insulator.

Breaking the time reversal symmetry (TRS) in a topological insulator (TI) by introducing a magnetic order gives rise to exotic quantum phenomena. One of the promising routes to inducing a magnetic order in a TI is utilizing magnetic proximity effect between a TI and a strong magnetic insulator (MI). In this article, we demonstrate a TI/MI heterostructure prepared through transferring a molecular beam epitaxy (MBE)-grown BiSe film onto a yttrium iron garnet (YIG) substrate via wet transfer. The transferred BiSe exhibits excellent quality over a large scale. Moreover, through wet transfer we are able to engineer the interface and perform a comparative study to probe the proximity coupling between BiSe and YIG under different interface conditions. A detailed investigation of both the anomalous Hall effect and quantum corrections to the conductivity in magnetotransport measurements reveals an induced magnetic order as well as TRS breaking in the transferred BiSe film on YIG. In contrast, a thin layer of AlO at the interface obstructs the proximity coupling and preserves the TRS, indicating the critical role of the interface in mediating magnetic proximity effect.