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Localized and collective magnetic excitations in the magnetic topological insulator Sn<sub>1-x</sub>Mn<sub>x</sub>Te

ORAL

Abstract

The nature of the magnetism dilute magnetic topological insulators (MTIs), controlled by atomic disorder and/or clustering and the competition between short- and long-range magnetic interactions, is not well understood. MTIs that develop ferromagnetic (FM) long-range order can host dissipationless electronic transport via the quantum anomalous Hall effect. We studied the magnetic excitations in a prototypical MTI, Sn0.95Mn0.05Te, using inelastic neutron scattering. Neutron diffraction and magnetization data indicate that our Sn0.95Mn0.05Te sample has no FM long-range order. However, we observe slow, collective FM fluctuations (<70 μeV), indicating proximity to FM order. We also find a series of sharp peaks originating from excitations of antiferromagnetically coupled Mn-Mn dimers with JAF =230 μeV. These dimers sit at next-nearest neighbor positions on the FCC sublattice, suggesting that Mn substitution is not completely random. The simultaneous presence of collective and localized components indicate that some Mn ions contribute to FM order and some form strongly-bound dimer singlets.

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Presenters

  • Robert McQueeney

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

Authors

  • Robert McQueeney

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

  • David Vaknin

    Ames Laboratory, Iowa State University, Ames Laboratory, Ames laboratory, Iowa State University

  • Santanu Pakhira

    Ames Laboratory

  • Daniel M. Pajerowski

    Oak Ridge National Lab, Oak Ridge National Laboratory

  • David C Johnston

    Iowa State University, Ames Laboratory, Ames, IA 50011, USA; Iowa State University, Ames, IA 50011, USA

  • Deborah Schlagel

    Ames Laboratory