Surface Magnetism and Proximity Effects in Hexaboride Thin Films

ORAL

Abstract

The unexpected ferromagnetism in alkaline hexaborides has attracted extensive research efforts to understand the exceptionally high Curie temperature sustained by low magnetic moments density. Here, we report the coexistence of ferromagnetic and superparamagnetic orders with 2D-type magnetic anisotropy in CaB6 and SrB6 thin films. Boron deficiency and closely correlated local oxidization were found at the film surface and its interface with the oxide substrate. These results suggest that the magnetism in hexaboride films is likely generated by two thin surface/interface layers with high concentration of boron vacancies which are energetically stabled by oxygen cation. Additionally, clear suppression of the superconductivity proximity effect in SmB6 film was observed when SmB6 was grown on top of the magnetic CaB6. Such results demonstrate the interesting perspective of engineering multifunctional heterostructures by coupling the surface magnetic layer with the diversity of other hexaboride materials.

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Presenters

  • Yanjun Ma

    Department of Physics and Astronomy, West Virginia University

Authors

  • Yanjun Ma

    Department of Physics and Astronomy, West Virginia University

  • Cheng Cen

    Department of Physics and Astronomy, West Virginia University, Physics and Astronomy, West Virginia Univ

  • Qiang Wang

    Department of Physics and Astronomy, West Virginia University, Physics and Astronomy, West Virginia University

  • 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