Detection of Magnetic Gap in Topological Surface States of MnBi2Te4

• Published in: 中国物理快报（英文版） Vol. 38; no. 10; pp. 92 - 111
• Main Authors: Hao-Ran Ji, Yan-Zhao Liu, He Wang, Jia-Wei Luo, Jia-Heng Li, Hao Li, Yang Wu, Yong Xu, Jian Wang
• Format: Journal Article
• Language: English
• Published: Frontier Science Center for Quantum Information,Beijing 100084,China%School of Materials Science and Engineering,Tsinghua University,Beijing 100084,China 01.11.2021; International Center for Quantum Materials,School of Physics,Peking University,Beijing 100871,China%Department of Physics,Capital Normal University,Beijing 100048,China%State Key Laboratory of Low-Dimensional Quantum Physics,Department of Physics,Tsinghua University,Beijing 100084,China; Beijing Academy of Quantum Information Sciences,Beijing 100193,China; CAS Center for Excellence in Topological Quantum Computation,University of Chinese Academy of Sciences,Beijing 100190,China; RIKEN Center for Emergent Matter Science (CEMS),Wako,Saitama 351-0198,Japan%International Center for Quantum Materials,School of Physics,Peking University,Beijing 100871,China; Department of Mechanical Engineering,Tsinghua University,Beijing 100084,China%State Key Laboratory of Low-Dimensional Quantum Physics,Department of Physics,Tsinghua University,Beijing 100084,China; Tsinghua-Foxconn Nanotechnology Research Center and Department of Physics,Tsinghua University,Beijing 100084,China%Tsinghua-Foxconn Nanotechnology Research Center and Department of Physics,Tsinghua University,Beijing 100084,China; State Key Laboratory of Low-Dimensional Quantum Physics,Department of Physics,Tsinghua University,Beijing 100084,China; Frontier Science Center for Quantum Information,Beijing 100084,China
• ISSN: 0256-307X
• DOI: 10.1088/0256-307X/38/10/107404

Recently,intrinsic antiferromagnetic topological insulator MnBi2Te4 has drawn intense research interest and leads to plenty of significant progress in physics and materials science by hosting quantum anomalous Hall effect,axion insulator state,and other quantum phases.An essential ingredient to realize these quantum states is the magnetic gap in the topological surface states induced by the out-of-plane ferromagnetism on the surface of MnBi2Te4.However,the experimental observations of the surface gap remain controversial.Here,we report the observation of the surface gap via the point contact tunneling spectroscopy.In agreement with theoretical calculations,the gap size is around 50 meV,which vanishes as the sample becomes paramagnetic with increasing temperature.The magnetoresistance hysteresis is detected through the point contact junction on the sample surface with an out-of-plane magnetic field,substantiating the surface ferromagnetism.Furthermore,the non-zero transport spin polarization coming from the ferromagnetism is determined by the point contact Andreev reflection spectroscopy.Combining these results,the magnetism-induced gap in topological surface states of MnBi2Te4 is revealed.