Direct observation of magnetic states in an actinide ferromagnet UMn2Ge2

ORAL

Abstract

We present studies of the magnetic domain structure of UMn2Ge2 single crystals using a home-built low temperature magnetic force microscope. The material has two distinct magnetic ordering temperatures, originating from the Mn and U moments. At room temperature, where the Mn moments dominate, flower-like domain patterns are observed. After exposing the sample to a one-tesla magnetic field near 40K, the evolution of the magnetic domains is imaged through zero field warming up to 200 K. Near the ordering temperature of the uranium moments a clear change in the domain wall motion is observed and can be explained by a 'Slingshot' mechanism. The anti-ferromagnetic coupling between Mn and U moments, responsible for the rapid domain wall motion, is further verified by local magnetic roughness measurement. The domain size analysis of the flower-like pattern reveals that the domain structure is consistent with a model of branching domains. In addition, an in-plane anisotropy is identified to be responsible for the highly self-similar flower-like pattern. Finally, there is also evidence of nanometer scale sub-domain structure inside each branching domain, comparable with what has been reported on uniaxial magnetic material Nd2Fe14B.

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Presenters

  • Xinzhou Tan

    Department of Physics, Univ of Texas

Authors

  • Xinzhou Tan

    Department of Physics, Univ of Texas

  • Alejandro De Lozanne

    Department of Physics, Univ of Texas

  • Morgann Berg

    Sandia National Laboratory

  • Jeehoon Kim

    Department of Physics, Pohang University of Science and Technology

  • Ryan Baumbach

    National High Magnetic Field Laboratory, Florida State University, National High Magnetic Field Lab, Florida State University, National High Magnetic Field Laboratory, NHMFL, National High Magnetic Field Laboratory/Florida State University, Natl High Magnetic Field Lab, NHMFL at Florida State University

  • Eric Bauer

    MPA-CMMS, Los Alamos National Laboratory, Los Alamos National Laboratory, Los Alamos Natl Lab, Condensed Matter and Magnetic Science Group, Los Alamos National Laboratory, Los Alamos National Lab, Condensed Matter and Magnet Science Group, Los Alamos National Laboratory

  • Joe Thompson

    MPA-CMMS, Los Alamos National Laboratory, Los Alamos National Laboratory, Condensed Matter and Magnetic Science Group, Los Alamos National Laboratory, Los Alamos Natl Lab, Condensed Matter and Magnet Science Group, Los Alamos National Laboratory

  • Filip Ronning

    MPA-CMMS, Los Alamos National Laboratory, Los Alamos Natl Lab, Los Alamos National Laboratory, Condensed Matter and Magnetic Science Group, Los Alamos National Laboratory, Condensed Matter and Magnet Science Group, Los Alamos National Laboratory