Evidence for ferromagnetic coupling at the doped topological insulator/ferrimagnetic insulator interface

• Main Authors: Liu, Wenqing (Author), He, Liang (Author), Zhou, Yan (Author), Murata, Koichi (Author), Jiang, Ying (Author), Wang, Yong (Author), Xu, Yongbing (Author), Zhang, Rong (Author), Wang, Kang. L. (Author), Onbasli, Mehmet C. (Contributor), Ross, Caroline A (Contributor)
• Other Authors: Massachusetts Institute of Technology. Department of Materials Science and Engineering (Contributor)
• Format: Article
• Language: English
• Published: American Institute of Physics (AIP), 2017-10-23T16:22:25Z.
• Subjects: Article
• Online Access: Get fulltext

 One of the major obstacles of the magnetic topological insulators (TIs) impeding their practical use is the low Curie temperature (T[subscript c] ). Very recently, we have demonstrated the enhancement of the magnetic ordering in Cr-doped Bi₂Se₃ by means of proximity to the high-T[subscript c] ferrimagnetic insulator (FMI) Y₃Fe₅O₁₂ and found a large and rapidly decreasing penetration depth of the proximity effect, suggestive of a different carrier propagation process near the TI surface. Here we further present a study of the interfacial magnetic interaction of this TI/FMI heterostrucutre. The synchrotron-based X-ray magnetic circular dichroism (XMCD) technique was used to probe the nature of the exchange coupling of the Bi[subscript 2-x] Cr [subscript x] Se₃/Y₃Fe₅O₁₂ interface. We found that the Bi[subscript 2-x] Cr [subscript x] Se₃ grown on Y₃Fe₅O₁₂ (111) predominately contains Cr ³⁺ cations, and the spin direction of the Cr³⁺ is aligned parallel to that of tetrahedral Fe³⁺ of the YIG, revealing a ferromagnetic exchange coupling between the Bi [subscript 2-x] Cr [subscript x] Se₃ and the Y₃Fe₅O₁₂.