Using X-ray beams with orbital angular momentum to probe an antiferromagnetic ground state

ORAL

Abstract

Artificial spin ice systems present an interesting platform to study magnetic interactions and dynamics. A square array of permalloy nanomagnets can be used to create an artificial antiferromagnetic lattice. Furthermore, topological defects such as edge dislocations can be introduced into the lattice. Resonant X-ray scattering from such an artificial spin ice with a defect of topological charge Z = 2 imparts an orbital angular momentum onto the scattered beam [1]. Here, we show how circular dichroism in the scattered diffraction pattern can be used to determine the ground state of the antiferromagnet and the magnetization configuration around the defect. By thermal cycling, two different degenerate ground states can be reached, and these can be differentiated using circular dichroism.

[1] J. S. Woods, X. M. Chen, et al. Phys. Rev. Lett. 126, 117201 (2021).

*This work was supported by the Laboratory Directed Research and Development Program of Lawrence Berkeley National Laboratory under U.S. Department of Energy Contract No. DE-AC02-05CH11231. This research used resources of the Advanced Light Source, a U.S. DOE Office of Science User Facility under contract no. DE-AC02-05CH11231. This work used Timepix based soft x-ray detector, development of which is supported by DOE through award RoyTimepixDetector. This work was performed in part at the University of Kentucky Center for Nanoscale Science and Engineering and Center for Advanced Materials, members of the National Nanotechnology Coordinated Infrastructure (NNCI), which is supported by the National Science Foundation (NNCI-2025075).

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Presenters

  • Margaret R McCarter

    • University of California, Berkeley
    • Lawrence Berkeley National Laboratory

Authors

  • Margaret R McCarter

    • University of California, Berkeley
    • Lawrence Berkeley National Laboratory

  • ARNAB SINGH

    • Lawrence Berkeley National Laboratory

  • Ahmad Us Saleheen

    • Lawrence Berkeley National Laboratory

  • Ryan Tumbleson

    • University of California, Santa Cruz

  • Anton S Tremsin

    • Space Sciences Laboratory, University of California, Berkeley

  • Justin S Woods

    • University of Kentucky

  • Lance E De Long

    • University of Kentucky

  • Jeffrey T Hastings

    • University of Kentucky

  • Sophie A Morley

    • Lawrence Berkeley National Laboratory

  • Sujoy Roy

    • Lawrence Berkeley National Laboratory
    • ALS, Lawrence Berkeley National Lab
    • LBL