Helictical phonon mode and spin phonon coupling of a-axis MnBi<sub>2</sub>Te<sub>4</sub> magnetic topological insulator

ORAL

Abstract

MnBi2Te4, made by intercalating a Mn-Te layer into a topological insulator Bi2Te3, is an antiferromagnetic topological insulator of abundant research potential due to its exotic physical properties—quantum anomalous Hall effect, Axion insulator, and Dirac semimetal depending on the magnetic state and its directions. Especially, the layered structure of MnBi2Te4 allows for the exhibition of many turntable capabilities, making it a valuable platform in device applications. In this article, we use Raman spectroscopy, which provides us with a structural fingerprint of the material, under various polarization and temperature dependent configurations to study the phonon modes of (100) direction of bulk MnBi2Te4. We observed intensity differences at 46, 113, and 146 cm-1 peaks between the right and left cross circular polarization configurations while they had the same intensity in co-circular polarization. In addition, A-axis MnBi2Te4 had rotation anisotropic polarization Raman spectra, with a 6-degree rotation when comparing above and below the transition temperature of MnBi2Te4. Our results contribute to understanding the phonon modes of (100) direction MnBi2Te4, and paves the way to tailoring its properties for use in promising emerging applications.

*J.H.K. and C.W.W acknowledge the support of UC Office of President (LFR-17-477237) and NSF (1810548 and 1611598). C.H. and N.N. thank the support of single crystal growth and characterization by the U.S. Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0021117.

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Presenters

  • Jin Ho Kang

    • Mesoscopic Optics and Quantum Electronics Laboratory, University of California, Los Angeles
    • Fang Lu Mesoscopic Optics and Quantum Electronics Laboratory, University of California, Los Angeles

Authors

  • Jin Ho Kang

    • Mesoscopic Optics and Quantum Electronics Laboratory, University of California, Los Angeles
    • Fang Lu Mesoscopic Optics and Quantum Electronics Laboratory, University of California, Los Angeles

  • Yujin Cho

    • Fang Lu Mesoscopic Optics and Quantum Electronics Laboratory, University of California, Los Angeles

  • Liangbo Liang

    • Oak Ridge National Lab
    • Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States

  • Chaowei Hu

    • Department of Physics and Astronomy and California NanoSystems Institute, University of California, Los Angeles

  • Alexander A. A Puretzky

    • Oak Ridge National Laboratory
    • Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States

  • Ni Ni

    • University of California, Los Angeles

  • Chee Wei Wong

    • University of California, Los Angeles