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Spin waves in the antiferromagnetic topological insulators MnBi<sub>2</sub>Te<sub>4</sub> and MnBi<sub>4</sub>Te<sub>7</sub>

ORAL

Abstract

MnBi2+2nTe4+3n are promising topological insulators (TI) where the natural intergrowth of magnetic layers and TI layers provides a unique platform for the study of interplay between magnetism and topological electronic states. Here we present our inelastic neutron scattering (INS) study on single crystals MnBi2Te4 and MnBi4Te7. We find that antiferromagnetic (AF) interlayer magnetic interactions in MnBi2Te4 which are vanishingly small in MnBi4Te7, need to be anisotropic for a consistent description of both INS and magnetization measurements. The modeling of two-dimensional intralayer ferromagnetic (FM) spin waves requires introduction of long-range and competing FM and AF magnetic interactions up to the seventh nearest neighbor. First principles calculations of insulating MnBi2Te4 support this model. The abnormal spin wave peak widths observed with INS could result from Mn vacancies/ Mn-Bi anti-site exchange as suggested by our spin dynamics simulation.

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Presenters

  • Bing Li

    Ames Laboratory, Iowa State University, Dept. of Physics and Astronomy, Ames, Ames Laboratory and Iowa State Univeristy, Ames Laboratory and Iowa State University, Ames, IA USA 50011

Authors

  • Bing Li

    Ames Laboratory, Iowa State University, Dept. of Physics and Astronomy, Ames, Ames Laboratory and Iowa State Univeristy, Ames Laboratory and Iowa State University, Ames, IA USA 50011

  • Liqin Ke

    Ames Laboratory, Ames Laboratory, U.S. Department of Energy, Ames, Iowa 50011, USA, Iowa State University, Ames Laboratory, U.S. Department of Energy

  • Simon Riberolles

    Physics and Astronomy, Iowa State University/Ames Laboratory, Division of Materials Science & Engineering, Ames Laboratory, Ames Laboratory and Iowa State Univeristy

  • Daniel Pajerowski

    Oak Ridge National Lab, Oak Ridge National Laboratory

  • Andreas Kreyssig

    Physics and Astronomy, Iowa State University/Ames Laboratory, Department of Physics and Astronomy, Ames Laboratory, Iowa State University, Ames Lab/Iowa State, Ames Laboratory, Iowa State University, Dept. of Physics and Astronomy, Ames, Ames Laboratory and Iowa State Univeristy

  • Benjamin G. Ueland

    Ames Laboratory, Iowa State University, Dept. of Physics and Astronomy, Ames, Ames Laboratory

  • Jiaqiang Yan

    Materials Science and Technology Division, Oak Ridge National Lab, Oak Ridge National Laboratory, University of Tennessee, Oak Ridge National Lab, Materials Science and Technology Division, Oak Ridge National Laboratory, Materials Science and Technology, Oak Ridge National Laboratory, Oak Ridge National Laboratory, Materials Science and Technology Division

  • Robert J. McQueeney

    Ames Laboratory, Iowa State University, Dept. of Physics and Astronomy, Ames, Ames Laboratory and Iowa State Univeristy