Understanding Magnetism at the Isostructural Phase Boundary in Multiferroic BiFeO3

ORAL

Abstract

Recent study suggests that in BiFeO$_{3 }$ (BFO) thin films epitaxial strain can lead to an isostructural change from distorted rhombohedral to a distorted tetragonal structure. In this work, ferromagnetic (or pyromagnetic) phase boundaries between these two phases in BFO thin films are induced from the as-grown state or by applying electric field using piezo- response force microscopy. Rhombohedral-like BFO is a G-type antiferromagnet with its easy plane in (111)-type planes. In depth density functional theory calculations suggest that tetragonal-like BFO is a C-type antiferromagnet with its easy plane in (110)-type planes. Detailed antiferromagnetic ordering of tetragonal-like BFO has been carefully studied using photo- emission electron spectroscopy with linear polarized x-rays. The isostructural phase boundary is magnetically frustrated because the transition between G-type and C-type antiferromagnetic ordering. X-ray magnetic circular dichroism is observed using photo-emission electron microscopy and spectroscopy with circular polarized x-ray.

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Authors

  • Qing He

    • Department of Physics, UC Berkeley

  • S.-Y. Yang

    • Department of Physics, UC Berkeley

  • R. Ramesh

    • University of California, Berkeley
    • Materials Sciences Division, Lawrence Berkeley National Laboratory
    • University of California Berkeley
    • Department of Physics, UC Berkeley

  • H.-J. Lin

    • National Synchrotron Radiation Research Center, Taiwan
    • National Synchrotron Radiation Research Center

  • C.-H. Wang

    • Department of Materials Science and Engineering, National Chiao Tung University

  • Y.-H. Chu

    • Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu, Taiwan
    • Department of Materials Science and Engineering, National Chiao Tung University