Lorentz electron microscopy methods for measuring nontrivial topological spin texture phenomena in real space

ORAL  · Invited

Abstract

The transmission electron microscope (TEM) is a powerful tool to directly observe a material's atomic structure and electromagnetic properties. Lorentz TEM (LTEM) provides a field-free imaging mode and it was in this way that the first real space images of topological magnetic skyrmions and their antiparticles, antiskyrmions, were acquired [1,2]. Combining LTEM with external stimuli such as magnetic fields, heat, and electric/thermal currents allows the direct observation of a spin texture’s in-situ response. The ability to drive controlled transformations between different magnetic states including magnetic (anti)skyrmions is at the heart of many spintronics applications. Of these, controlled thermal current-driven transformations are especially desirable, as they enable the recycled use of heat lost in modern industrial energy cycles. Here, we review field-free TEM methods [3], demonstrate a thermal current-driven topological transformation between magnetic textures in the recently discovered antiskyrmion-host magnet (Fe0.63Ni0.3Pd0.07)3P and reveal that the antiskyrmions intrinsic to (Fe0.63Ni0.3Pd0.07)3P are hybrid topological strings composed of skyrmions on the surfaces and an antiskyrmion in the bulk using vector field electron tomography. Such topological complexity necessitates the existence of a Bloch point quadrupole, which we present in high resolution for the first time.

[1] X. Z. Yu, et al., Nature 465, 901 (2010).

[2] A. K. Nayak, et al., Nature 548, 561 (2017).

[3] D. V. Christensen et al., J. Phys. Mater. 7, 032501 (2024).

*Research conducted as part of a user project at the Center for Nanophase Materials Sciences and sponsored by the Laboratory Directed Research and Development Program of Oak Ridge National Laboratory, managed by UT-Battelle, LLC, for the US Department of Energy. Work supported by Grants-In-Aid for Scientific Research (Grant No. 19H00660) from the Japan Society for the Promotion of Science (JSPS), by the Japan Science and Technology Agency (JST) CREST program (Grant No. JPMJCR20T1), Japan, and by the RIKEN TRIP initiative (Many-body Electron Systems and Advanced General Intelligence for Science Program).

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Publication: 1. Yasin, Fehmi Sami, et al. "Bloch point quadrupole constituting hybrid topological strings revealed with electron holographic vector field tomography." Advanced Materials 36.16 (2024): 2311737.
2. Yasin, Fehmi Sami, et al. "Heat current-driven topological spin texture transformations and helical q-vector switching." Nature Communications 14.1 (2023): 7094.

Presenters

  • Fehmi S Yasin

    • Center for Nanophase Materials Sciences, Oak Ridge National Laboratory
    • Oak Ridge National Laboratory

Authors

  • Fehmi S Yasin

    • Center for Nanophase Materials Sciences, Oak Ridge National Laboratory
    • Oak Ridge National Laboratory

  • Jan Masell

    • Karlsruhe Institute of Technology
    • Institute of Theoretical Solid State Physics Karlsruhe Institute of Technology (KIT)

  • Yoshio Takahashi

    • Research and Development Group, Hitachi Ltd.

  • Tetsuya Akashi

    • Research and Development Group, Hitachi Ltd.

  • Norio Baba

    • Research Institute for Science and Technology, Kogakuin University

  • Kosuke Karube

    • RIKEN
    • RIKEN Center for Emergent Matter Science (CEMS)

  • Daisuke Shindo

    • RIKEN

  • Takahisa Arima

    • RIKEN Center for Emergent Matter Science, Department of Advanced Materials Science, University of Tokyo

  • Yasujiro Taguchi

    • RIKEN
    • RIKEN CEMS
    • RIKEN Center for Emergent Matter Science (CEMS)

  • Yoshinori Tokura

    • RIKEN Center for Emergent Matter Science (CEMS), Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), The University of Tokyo
    • Univ of Tokyo
    • The University of Tokyo, RIKEN Center for Emergent Matter Science (CEMS), Tokyo college, The University of Tokyo
    • RIKEN Center for Emergent Matter Science (CEMS); Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), Univ. of Tokyo; Tokyo College, Univ. of Tokyo
    • RIKEN Center for Emergent Matter Science (CEMS), Department of Applied Physics, Quantum-Phase Electronics Center (QPEC) and Tokyo College, University of Tokyo

  • Toshiaki Tanigaki

    • Research and Development Group, Hitachi Ltd.

  • Xiuzhen Yu

    • RIKEN Center for Emergent Matter Science