Experimental evidence on the proximity effect in topological insulator/magnetic insulator epitaxial layers

Shang-Fan Lee^1*, J. Kwo², M. Hong³

¹Institute of Physics, Academia Sinica, Taipei, Taiwan
²Department of Physics, National Tsing Hua University, Hsinchu, Taiwan
³Department of Physics, National Taiwan University, Taipei, Taiwan

* Presenter:Shang-Fan Lee, email:leesf@gate.sinica.edu.tw

Magnetic proximity effect (MPE) induced signatures of interfacial magnetic anisotropy and exchange gap opening in the interfacial band structure are reported for bilayer structure of Bi2Se3 thin films and iron garnets, which have either in-plane or perpendicular magnetic anisotropy. Negative magnetoresistance (MR) was detected and attributed to an emergent weak localization (WL) effect superimposing on a weak antilocalization (WAL) one, showing positive MR background. When thickness is varied, we see systematic change attributed to the WL effect originates from the time-reversal-symmetry breaking of the surface states by the exchange coupling. Clear Anomalous Hall effect (AHE) and anisotropic magnetoresistance (AMR) characteristic are observed despite the insulating nature of the ferrimagnetic garnet. Coexistence of the MPE-induced ferromagnetism and the finite exchange gap in the surface state band structure suggests the possibility of pursuing spin-orbit and topology driven transport phenomena, the quantum anomalous Hall effect (QAHE) and the topological magnetoelectric effect (TME) in these heterostructures at relatively high temperatures.

Keywords: topological superconductor, topological surface state, proximity effect, weak antilocalization, Anomalous Hall effect