Enhanced Optical Band Gap in Ultrathin Epitaxial Ferromagnetic Insulator GdN Films

ORAL

Abstract

Full understanding of the optical and magnetic properties of insulating ferromagnetic GdN epitaxial ultrathin films would enable proximity coupling it to Graphene and 2D layer systems. Moreover, exchange split band of GdN acting as a spin-filter would offer the ideal means for spin polarized current injection in the above systems as well as into superconductors. With this objective we investigated the intrinsic magnetic and optical behavior of GdN films reactively rf sputtered in a UHV system under various conditions to optimize the high quality of films and reduce their defects. This in turn can enable GdN to achieve high spin filtering and the needed effective interfacial exchange interaction for 2D systems. In the range of film thickness (2 to 300nm, protected by AlN film) the dependence of direct and indirect band-gap energies as well as the ferromagnetic ordering temperature and magnetic moment was studied: optical gap increased while the magnetic moment reduced with film thickness reduction.

*This work was supported by NSF (DMR 1700137), ONR (N00014-16-1-2657), Center for Integrated Quantum Materials (NSF DMR-1231319) and Brazilian agencies CAPES (Gilvania Vilela/POS-DOC-88881.120327/2016-01), FACEPE and CNPq.

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Presenters

  • Gilvania Da Silva Vilela

    • Plasma Science and Fusion Center and Francis Bitter Magnet Laboratory, MIT and Universidade de Pernambuco
    • Plasma Science and Fusion Center, and Francis Bitter Magnet Laboratory, MIT and Universidade de Pernambuco

Authors

  • Gilvania Da Silva Vilela

    • Plasma Science and Fusion Center and Francis Bitter Magnet Laboratory, MIT and Universidade de Pernambuco
    • Plasma Science and Fusion Center, and Francis Bitter Magnet Laboratory, MIT and Universidade de Pernambuco

  • Geetha Berera

    • Department of Materials Science and Engineering, MIT

  • Gregory Stephen

    • Department of Physics, Northeastern University
    • Northeastern University

  • Xavier Gratens

    • Departamento de Fisica dos Materiais, Universidade de Sao Paulo

  • Pavel Usachev

    • Departamento de Fisica dos Materiais, Universidade de Sao Paulo

  • Don Heiman

    • Department of Physics, Northeastern University

  • Andre Henriques

    • Departamento de Fisica dos Materiais, Universidade de Sao Paulo

  • Jagadeesh Moodera

    • Dept. Of Physics, Plasma Science and Fusion Center and Francis Bitter Magnet Lab, Massachusetts Institute of Technology
    • MIT
    • Department of Physics, Massachusetts Institute of Technology
    • Massachusetts Institute of Technology
    • Department of Physics, Plasma Science and Fusion Center, and Francis Bitter Magnet Lab, Massachusetts Institute of Technology
    • Plasma Science and Fusion Center and Francis Bitter Magnet Laboratory, MIT
    • Plasma Science and Fusion Center, and Francis Bitter Magnet Laboratory, and Department of Physics, MIT
    • Francis Bitter Magnet Laboratory and Plasma Science and Fusion Center, MASSACHUSETTS INSTITUTE OF TECHNOLOGY
    • Plasma Science and Fusion Center and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology
    • Physics, Francis Bitter Magnet Laboratory, Plasma Science and Fusion Center, Massachusetts Institute of Technology
    • Department of Physics, MIT, Cambridge, MA, 02139