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Skyrmion lattice creep at ultra-low current densities

ORAL

Abstract

Magnetic skyrmions are well-suited for encoding information because they are nano-sized, topologically stable, and only require ultra-low critical current densities jc to depin from the underlying atomic lattice. Above jc skyrmions exhibit well-controlled motion, making them prime candidates for race-track memories. In thin films thermally-activated creep motion of isolated skyrmions was observed below jc as predicted by theory. Uncontrolled skyrmion motion is detrimental for race-track memories and is not fully understood. Notably, the creep of skyrmion lattices in bulk materials remains to be explored. Here we show using resonant ultrasound spectroscopy - a probe highly sensitive to the coupling between skyrmion and atomic lattices - that in the prototypical skyrmion lattice material MnSi depinning occurs at jc that is only 4 percent of jc. Our experiments are in excellent agreement with Anderson-Kim theory for creep and allow us to reveal a new dynamic regime at ultra-low current densities characterized by thermally-activated skyrmion-lattice-creep with important consequences for applications.
References:
[1] Y. Luo et al., arXiv: 2009.11656 (2020), Quantum Materials in press.
[2] Y. Luo et al., Phys. Rev. B 97, 104423 (2018)

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Presenters

  • Yongkang Luo

    University of California, Los Angeles, Huazhong University of Science & Technology, Huazhong University of Science and Technology

Authors

  • Yongkang Luo

    University of California, Los Angeles, Huazhong University of Science & Technology, Huazhong University of Science and Technology

  • Shi-Zeng Lin

    Los Alamos National Laboratory, Los Alamos National Lab, Los Alamos Natl Lab, Theoretical Division, T-4, Los Alamos National Laboratory

  • Maxime Leroux

    Los Alamos National Lab

  • David Michael Fobes

    Los Alamos National Laboratory, Los Alamos National Lab

  • Eric D Bauer

    Los Alamos National Laboratory, Los Alamos National Lab, Los Alamos National laboratory, Los Alamos Natl Lab, Condensed Matter and Magnet Science Group, Los Alamos National Laboratory, Los Alamos National LAborator

  • Joe Thompson

    Los Alamos National Lab, Los Alamos National laboratory, Los Alamos National Laboratory

  • Marc Janoschek

    Paul Scherrer Institute

  • Boris A Maiorov

    Los Alamos National Lab, Los Alamos Natl Lab