Observation of Vortex/Meron Pairs at Room Temperature in a planar α-Fe<sub>2</sub>O<sub>3</sub>/Co Heterostructure.

ORAL

Abstract

Vortices are among the simplest topological structures. They occur whenever a flow field `whirls' around a one-dimensional core, and are ubiquitous to many branches of physics. In the crystalline state, vortex formation is rare, since it is generally hampered by long-range interactions. Here, we present the discovery of a novel form of crystalline vortices in antiferromagnetic (AFM) hematite (α-Fe2O3) epitaxial films, in which the primary whirling parameter is the non-ferroics staggered magnetisation. Remarkably, ferromagnetic (FM) topological objects with the same winding number of the α-Fe2O3 vortices are imprinted onto an ultra-thin Co ferromagnetic over-layer by interface exchange. Our data suggest that the FM objects are merons (half-skyrmions), and that the vortex/meron pairs are relatively robust well beyond the Co coercive field, but can be manipulated by the application of a larger in-plane magnetic field (Hpar~100mT) , giving rise to large-scale vortex-antivortex annihilation.

*We acknowledge EPSRC grant No. EP/M020517/1 (Oxford), NSF-DMREF Grant No. DMR-1629270 and Army Research Office grant W911NF-13-1-0486 (Madison) and the Diamond Light Source (proposal SI16388) for beamtime on beamline I06.

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Presenters

  • Paolo G. Radaelli

    • Clarendon Laboratory, Department of Physics, University of Oxford

Authors

  • Paolo G. Radaelli

    • Clarendon Laboratory, Department of Physics, University of Oxford

  • Francis Chmiel

    • Clarendon Laboratory, University of Oxford
    • Clarendon Laboratory, Department of Physics, University of Oxford
    • Physics, University of Oxford

  • Noah Waterfield Price

    • Clarendon Laboratory, University of Oxford
    • Clarendon Laboratory, Department of Physics, University of Oxford
    • Physics, University of Oxford

  • Roger Johnson

    • Clarendon Laboratory, University of Oxford
    • Clarendon Laboratory, Department of Physics, University of Oxford
    • Physics, University of Oxford

  • Anne Lamirand

    • Diamond Light Source Ltd.

  • Jonathan Schad

    • Matls Sci & Eng, University of Wisconsin-Madison
    • Department of Materials Science and Engineering, University of Wisconsin-Madison

  • Chang-Beom Eom

    • University of Wisconsin-Madison
    • Univ of Wisconsin-Madison
    • Univ of Wisconsin, Madison
    • Department of Material Science and Engineering, University of Wisconsin-Madison
    • Matls Sci & Eng, University of Wisconsin-Madison
    • University of Wisconsin
    • Department of Materials Science and Engineering, University of Wisconsin-Madison
    • University of Wisconsin–Madison
    • MS&E, University of Wisconsin
    • Physics, University of Wisconsin–Madison
    • Department of Materials Science and Engineering, University of Wisconsin - Madison