Uncorrelated magnetic domains in decoupled SrFe12O19/Co hard/soft bilayers

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaperJournal articleResearchpeer-review

DOI

  • Guiomar D. Soria, CSIC - Institute of Physical Chemistry Rocasolano
  • ,
  • Cecilia Granados-Miralles, CSIC - Institute of Ceramics and Glass
  • ,
  • Anna Mandziak, CSIC - Institute of Physical Chemistry Rocasolano, Alba Synchrotron Light Facility, CELLS, Barcelona E-08290, Spain
  • ,
  • Petra Jenuš, J. Stefan Institute
  • ,
  • Matilde Saura-Múzquiz, University of Sydney
  • ,
  • Mogens Christensen
  • Michael Foerster, Alba Synchrotron Light Facility, CELLS, Barcelona E-08290, Spain
  • ,
  • Lucía Aballe, Alba Synchrotron Light Facility, CELLS, Barcelona E-08290, Spain
  • ,
  • José F. Fernández, CSIC - Institute of Ceramics and Glass
  • ,
  • Juan de la Figuera, CSIC - Institute of Physical Chemistry Rocasolano
  • ,
  • Adrián Quesada, CSIC - Institute of Ceramics and Glass

Composites of magnetically hard and soft phases are present in multiple and diverse applications, ranging from bulk permanent magnets in motors and generators to state-of-the-art recording media devices. The nature of the magnetic coupling between the hard and soft phases is of great technological relevance, as the macroscopic properties of the functional composite material ultimately depend on the atomic-scale interactions between phases. In this work, the hard/soft bilayer system SrFe12O19/Co has been studied based on photoemission electron microscopy combined with x-ray absorption and magnetic circular dichroism. Our experiments show that the magnetization of the hard magnetic oxide has a direction perpendicular to the layer plane, whereas the magnetization of the soft metallic overlayer remains in-plane. As a consequence, the magnetic domain patterns observed for the hard and soft phases are very different and completely uncorrelated to one another, indicating that no soft spins align with the hard phase by pure magnetodipolar arguments. The results are understood as the consequence of an absence of exchange-coupling between phases, in a scenario in which the shape anisotropy of the soft layer overcomes the Zeeman energy of the perpendicular magnetic field generated by the hard ferrite. Micromagnetic simulations of our system predict that low degrees of exchange-coupling effectively prevent substantial softening of the composite and lead to the alignment of soft and hard magnetic moments. A strategy thus emerges for the development of future hard-soft magnets, based on minimizing the degree of exchange-coupling while avoiding complete uncoupling.

Original languageEnglish
Article number054003
JournalJournal of Physics D: Applied Physics
Volume54
Issue5
Number of pages8
ISSN0022-3727
DOIs
Publication statusPublished - Feb 2021

    Research areas

  • Hard/soft bilayers, Magnetic energy, Micromagnetic simulations, Microscopy, Strontium ferrite, XMCD-PEEM

See relations at Aarhus University Citationformats

ID: 213164175