Experimental observation of magnetic hopfions in multilayer disks

ORAL

Abstract

Topological solitons are currently of high interest to condensed matter physics. Among those, magnetic skyrmions (Sk) are two-dimensional objects with a continuous winding of the magnetization, and magnetic Hopfions are 3D topological solitons that can be formed from a closed loop of a twisted skyrmion string. Whereas intense research with magnetic Sks has already led to a deep understanding and potential applications in advanced storage and logic devices1,2, the experimental validation of magnetic Hopfions has been elusive so far. Theoretical models suggest that Hopfions can be stabilized in frustrated or chiral magnetic systems, and kπ skyrmions, aka target skymions (TSk) can be transformed into Hopfions by adapting their perpendicular magnetic anisotropy3,4.
We present experimental evidence of magnetic Hopfions in magnetic Ir/Co/Pt multilayers shaped into nanoscale disks, which are known to host TSks5. Their distinct 3D spin texture was observed by combining two magnetic soft x-ray microscopies, namely surface sensitive X-PEEM, and bulk sensitive full field MTXM.
1 A. Fert,et al, Nat. Nanotech. 8 152 (2013)
2 A. Soumyanarayanan, et al. Nat. Mat. 16 898 (2017)
3 P. Sutcliffe, JPhysA (2018)
4 Y. Liu et al PRB 98 174437 (2018)
5 N. Kent et al. APL 115 112404 (2019)

*Funded by US DOE.

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Presenters

  • Peter Fischer

    • Lawrence Berkeley National Laboratory
    • University of California, Santa Cruz

Authors

  • Noah Kent

    • Lawrence Berkeley National Laboratory

  • Neal Reynolds

    • Lawrence Berkeley National Laboratory

  • David Raftrey

    • University of California, Santa Cruz
    • Lawrence Berkeley National Laboratory

  • Ian T.G. Campbell

    • Lawrence Berkeley National Laboratory

  • Selven Virasawmy

    • Lawrence Berkeley National Laboratory

  • Scott Dhuey

    • Lawrence Berkeley National Laboratory

  • Rajesh V Chopdekar

    • Advanced Light Source, Lawrence Berkeley National Lab
    • University of California, Davis
    • Lawrence Berkeley National Laboratory

  • Aurelio Hierro-Rodriguez

    • University of Oviedo, Spain
    • University Oviedo

  • Andrea Sorrentino

    • ALBA Synchrotron, Spain
    • ALBA Synchrotron

  • Eva Pereiro

    • ALBA Synchrotron, Spain
    • ALBA Synchrotron

  • Salvador Ferrer

    • ALBA Synchrotron, Spain
    • ALBA Synchrotron

  • Frances Hellman

    • Physics, University of California, Berkeley
    • Lawrence Berkeley National Laboratory
    • University of California Berkeley

  • Paul M. Sutcliffe

    • U Durham

  • Peter Fischer

    • Lawrence Berkeley National Laboratory
    • University of California, Santa Cruz