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Phononic control of magnetism in a topological insulator

ORAL

Abstract

Magnetism in topological materials can give rise to unconventional topological phases that exhibit intriguing behavior such as the quantized magnetoelectric effect and the quantum anomalous Hall effect. The key to harnessing these properties in device applications lies in the ability to control magnetism. In this work, we demonstrate for the first time, the optical control of magnetism in a topological insulator. This is achieved in the recently discovered magnetic topological insulator MnBi2Te4.

First, using Raman spectroscopy, we detect that optical phonons strongly modulate the exchange interaction, resulting in a renormalization of phonon energies and lifetimes across the magnetic transition. These changes are the largest observed in any two-dimensional material to date. We exploit this strong coupling to optically engineer the spin Hamiltonian, through ultrafast modulation of the exchange interaction by coherent phonons. Using a time-resolved Kerr effect probe, we detect a resultant coherent modulation of the magnetization. Our work thus unlocks a novel mode of control of magnetism, offering new opportunities in the coherent manipulation of topological materials.

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Presenters

  • Hari Padmanabhan

    Pennsylvania State University, Department of Material Science and Engineering, Penn State University

Authors

  • Hari Padmanabhan

    Pennsylvania State University, Department of Material Science and Engineering, Penn State University

  • Nathan Koocher

    Northwestern University

  • Peter Kim

    University of California, San Diego, UC San Diego

  • Maxwell Poore

    University of California, San Diego, UC San Diego

  • Vladimir A Stoica

    Pennsylvania State University, Argonne National Laboratory, Department of Physics, University of Michigan

  • Danilo Puggioni

    Northwestern University

  • Huaiyu Wang

    Department of Material Science and Engineering, Penn State University, Pennsylvania State University

  • Seng Huat Lee

    Pennsylvania State University, Department of Physics, Pennsylvania State University, Physics, The Pennsylvania State University, 2D Crystal Consortium, Materials Research Institute, Penn State University, Materials Research Institute, Pennsylvania State University

  • Maxwell Wetherington

    Pennsylvania State University

  • Richard D Schaller

    Northwestern University, Center for Nanoscale Materials, Argonne National Laboratory

  • Richard Averitt

    University of California, San Diego, University of California San Diego, UC San Diego, Physics, University of California San Diego, Department of Physics, University of California, San Diego, University of California

  • James M Rondinelli

    Northwestern University, McCormick School of Engineering, Department of Materials Science and Engineering, Northwestern University, Department of Materials Science and Engineering, Northwestern University

  • Venkatraman Gopalan

    Pennsylvania State University, Material Science and Engineering, Pennsylvania State University, Department of Material Science and Engineering, Penn State University, Department of Materials Science and Engineering, Pennsylvania State University, Materials Science and Engineering, Pennsylvania State University