Interplay between Strain-Stabilized Ferromagnetism and Charge Transport in Epitaxial LaCoO3-δ Thin Films

ORAL

Abstract

The presence of ferromagnetic (FM) order in epitaxial LaCoO3 (LCO) thin films, in stark contrast to bulk, has gathered substantial recent attention. Due to the insulating nature of this strain-stabilized FM, however, little attention has been paid to electronic transport. Here, we present a systematic study of epitaxial LCO films (8-22 nm thick) grown under both tensile (on SrTiO3 and LSAT) and compressive strain (on LaAlO3 and SrLaAlO4), emphasizing not only magnetism but also transport. Tensile films exhibit ferromagnetism with saturation magnetization 1-1.5 μB/Co and Curie temperature ~80 K, consistent with prior work. Polarized neutron reflectometry has also been performed, revealing a uniform magnetization depth profile with thickness. Most notably, transport, which is semiconducting in all cases, reveals an unanticipated correlation between strain-state and majority carrier type, supported by density functional theory calculations suggesting significant changes in conduction band structure under strain. This provides important clues to the origin of FM in this material.

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Presenters

  • VIPUL CHATURVEDI

    University of Minnesota

Authors

  • VIPUL CHATURVEDI

    University of Minnesota

  • Jeffery J Walter

    University of Minnesota

  • Arpita Paul

    University of Minnesota

  • Jong S Jeong

    University of Minnesota

  • Alexander Grutter

    National Institute of Standards and Technology, NIST, NIST Center for Neutron Research, NIST Gaithersburg, Neutron-Condensed Matter Science Group, NIST, NIST Center for Neutron Research

  • Brian Kirby

    National Institute of Standards and Technology, NIST Center for Neutron Research, National Institute for Standards and Technology, NIST Center for Neutron Research

  • Julie Borchers

    National Institute of Standards and Technology, NIST Center for Neutron Research, National Institute of Standards and Technology

  • K. Andre Mkhoyan

    Chemical Engineering and Materials Science, University of Minnesota - Twin Cities, University of Minnesota, Chemical Engineering and Materials Science, University of Minnesota

  • Turan Birol

    Department of Chemical Engineering and Material science, University of Minnesota, Chemical Engineering and Materials Science, University of Minnesota - Twin Cities, University of Minnesota, Department of Chemical Engineering and Materials Science, University of Minnesota, Department of Chemical Engineering and Materials Science, UNIVERSITY OF MINNESOTA

  • Chris Leighton

    Chemical Engineering and Materials Science, University of Minnesota, Univ of Minn - Minneapolis, University of Minnesota