Direct imaging of the internal Bloch-components of polar-skyrmions and anti-hedgehogs in oxide heterostructures

ORAL

Abstract

Emergent topological textures in ferroelectric heterostructures such as polar vortices and skyrmions has been the playground for exploring new phases and phenomena, exhibiting exotic functionalities including emergent chirality and local negative capacitance. These topologies can be realized in superlattices of (PbTiO3)n/(SrTiO3)n, either on a rigid substrate or fully lifted-off as 2D-like membranes. The electric analog of magnetic skyrmions, nm-scale polar-skyrmion bubbles, was recently observed yet their local dipole configurations and response to external stimuli are less explored. Results of electron diffraction-imaging show that the in-plane polarization curling direction is preserved (counter-clockwise, CCW) whether the skyrmion bubbles are elongated, merged, or broken apart under the perturbation of a focused electron probe. Furthermore, an ordered skyrmion square lattice appeared when heated to 373 K, in which a CCW curling dipole moment was surrounded by arrays of anti-hedgehogs and clockwise curling dipole moments.

*Research supported by AFOSR Hybrid Materials MURI (FA9550-18-1-0480), facilities support from the NSF (DMR-1429155, DMR-1719875).

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Presenters

  • Yu-Tsun Shao

    • Applied and Engineering Physics, Cornell University

Authors

  • Yu-Tsun Shao

    • Applied and Engineering Physics, Cornell University

  • Sujit Das

    • University of California, Berkeley, USA
    • Department of Materials Science and Engineering, University of California, Berkeley
    • University of California, Berkeley
    • Materials Science and Engineering, University of California, Berkeley

  • Ruijuan Xu

    • Department of Applied Physics, Stanford University
    • Applied Physics, Stanford University

  • Swathi Chandrika

    • Applied and Engineering Physics, Cornell University

  • Harold Hwang

    • Institute for Materials and Energy Sciences, Stanford University
    • Stanford University
    • Department of Applied Physics, Stanford University
    • Applied Physics, Stanford University
    • SIMES, SLAC
    • Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
    • SLAC National Accelerator Lab.
    • Physics, Stanford University
    • Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory

  • Ramamoorthy Ramesh

    • Department of Materials Science and Engineering, UC Berkeley
    • University of California, Berkeley, USA
    • University of California, Berkeley
    • Materials Science and Engineering, University of California, Berkeley
    • Department of Materials Science and Engineering, University of California, Berkeley
    • Department of Materials Science and Engineering,, University of California, Berkeley, California 94720, USA

  • David Anthony Muller

    • Cornell University
    • School of Applied and Engineering Physics, Cornell University
    • Applied and Engineering Physics, Cornell University
    • School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA