title: Weak localization effect in topological insulator micro flakes grown on insulating ferrimagnet BaFe₁₂O₁₉.
abstract: Many exotic physics anticipated in topological insulators require a gap to be opened for their topological surface states by breaking time reversal symmetry. The gap opening has been achieved by doping magnetic impurities, which however inevitably create extra carriers and disorder that undermine the electronic transport. In contrast, the proximity to a ferromagnetic/ferrimagnetic insulator may improve the device quality, thus promises a better way to open the gap while minimizing the side-effects. Here, we grow thin single-crystal Sb1.9Bi0.1Te3 micro flakes on insulating ferrimagnet BaFe12O19 by using the van der Waals epitaxy technique. The micro flakes show a negative magnetoresistance in weak perpendicular fields below 50 K, which can be quenched by increasing temperature. The signature implies the weak localization effect as its origin, which is absent in intrinsic topological insulators, unless a surface state gap is opened. The surface state gap is estimated to be 10 meV by using the theory of the gap-induced weak localization effect. These results indicate that the magnetic proximity effect may open the gap for the topological surface attached to BaM insulating ferrimagnet. This heterostructure may pave the way for the realization of new physical effects as well as the potential applications of spintronics devices.
authors.affiliation: High Magnetic Field Laboratory, the Chinese Academy of Sciences, Hefei 230031, the People's Republic of China; University of Science and Technology of China, Hefei 230026, The People's Republic of China.
authors.forename: Guolin
authors.initials: G
authors.lastname: Zheng
authors.affiliation: High Magnetic Field Laboratory, the Chinese Academy of Sciences, Hefei 230031, the People's Republic of China; University of Science and Technology of China, Hefei 230026, The People's Republic of China.
authors.forename: Ning
authors.initials: N
authors.lastname: Wang
authors.affiliation: High Magnetic Field Laboratory, the Chinese Academy of Sciences, Hefei 230031, the People's Republic of China; University of Science and Technology of China, Hefei 230026, The People's Republic of China.
authors.forename: Jiyong
authors.initials: J
authors.lastname: Yang
authors.affiliation: High Magnetic Field Laboratory, the Chinese Academy of Sciences, Hefei 230031, the People's Republic of China; University of Science and Technology of China, Hefei 230026, The People's Republic of China.
authors.forename: Weike
authors.initials: W
authors.lastname: Wang
authors.affiliation: High Magnetic Field Laboratory, the Chinese Academy of Sciences, Hefei 230031, the People's Republic of China; University of Science and Technology of China, Hefei 230026, The People's Republic of China.
authors.forename: Haifeng
authors.initials: H
authors.lastname: Du
authors.affiliation: High Magnetic Field Laboratory, the Chinese Academy of Sciences, Hefei 230031, the People's Republic of China; University of Science and Technology of China, Hefei 230026, The People's Republic of China.
authors.forename: Wei
authors.initials: W
authors.lastname: Ning
authors.affiliation: High Magnetic Field Laboratory, the Chinese Academy of Sciences, Hefei 230031, the People's Republic of China; University of Science and Technology of China, Hefei 230026, The People's Republic of China.|Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, The People's Republic of China.
authors.forename: Zhaorong
authors.initials: Z
authors.lastname: Yang
authors.affiliation: Department of Physics, South University of Science and Technology of China, Shenzhen, China.
authors.forename: Hai-Zhou
authors.initials: HZ
authors.lastname: Lu
authors.affiliation: High Magnetic Field Laboratory, the Chinese Academy of Sciences, Hefei 230031, the People's Republic of China; University of Science and Technology of China, Hefei 230026, The People's Republic of China.|Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, The People's Republic of China.
authors.forename: Yuheng
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: High Magnetic Field Laboratory, the Chinese Academy of Sciences, Hefei 230031, the People's Republic of China; University of Science and Technology of China, Hefei 230026, The People's Republic of China.|Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, The People's Republic of China.|Hefei Science Center, Chinese Academy of Sciences, Hefei 230031, Anhui, China.
authors.forename: Mingliang
authors.initials: M
authors.lastname: Tian