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Electronic structure of topological insulator Bi<sub>2</sub>Se<sub>3</sub> thin films on thulium iron garnet heterostructures

ORAL

Abstract

Breaking time-reversal symmetry (TRS) in topological insulator (TI) leads to exotic phenomena such as quantum anomalous Hall effect (QAHE). The novel phenomena originated from a gap opening at the Dirac surface state by exchange interaction with magnetic elements. Magnetically doped TI was first reported to exhibit such an exchange gap, but the observation temperature of QAHE was less than 2 K. Another way to break TRS is through interfacial magnetic proximity effect (MPE) in TI/ferromagnetic insulator bilayer with a strong ferromagnetism and uniform interfacial magnetization. In this work, TI films Bi2Se3 were grown by molecular beam epitaxy on ferromagnetic thulium iron garnet (TmIG) with perpendicular magnetic anisotropy and high TC above 500K. The band structures of 2-6 quintuple layer (QL) Bi2Se3/TmIG bilayers were investigated by angle-resolved photoemission spectroscopy. Comparative study in 2-6 QL Bi2Se3/sapphire was also performed. The energy gap opening at the surface state of Bi2Se3/TmIG is larger than that of Bi2Se3/sapphire by about 20 meV. The larger surface state gap of Bi2Se3/TmIG could be induced by MPE, on top of hybridization of top and bottom surfaces. Our study demonstrates the opportunity of probing interfacial band of TI-based heterostructures.

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Presenters

  • Sheng-Wen Huang

    Department of Physics, National Tsing Hua University, Hsinchu, Taiwan, Natl Tsing Hua Univ, Department of Physics, National Tsing Hua University, Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan

Authors

  • Sheng-Wen Huang

    Department of Physics, National Tsing Hua University, Hsinchu, Taiwan, Natl Tsing Hua Univ, Department of Physics, National Tsing Hua University, Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan

  • Keng-Yung Lin

    Graduate Institute of Applied Physics and Department of Physics, National Taiwan University, Taipei, Taiwan, Natl Taiwan Univ

  • Chun-Chia Chen

    Department of Physics, National Tsing Hua University, Hsinchu, Taiwan, Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan

  • Mengxin Guo

    Department of Physics, National Tsing Hua University, Hsinchu, Taiwan, Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan

  • Chao-Kai Cheng

    Graduate Institute of Applied Physics and Department of Physics, National Taiwan University, Taipei, Taiwan, Department of Physics, National Taiwan University

  • Cheng-Maw Cheng

    National Synchrotron Radiation Research Center, National Synchrotron Radiation Research Center, Hsinchu, Taiwan, Natl Synchrotron Rad Res Ctr

  • Minghwei Hong

    Graduate Institute of Applied Physics and Department of Physics, National Taiwan University, Taipei, Taiwan, Natl Taiwan Univ, Department of Physics, National Taiwan University, Graduate Institute of Applied Physics and Department of Physics, National Taiwan University, Taipei 10617, Taiwan, Department of Physics, National Taiwan University, Taipei, Taiwan

  • Jueinai Kwo

    Department of Physics, National Tsing Hua University, Hsinchu, Taiwan, Natl Tsing Hua Univ, Department of Physics, National Tsing Hua University, Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan