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Title: Magnetic structures and excitations in a multiferroic Y-type hexaferrite BaSrCo2Fe11AlO22

Here, we have investigated magnetic orders and excitations in a Y-type hexaferrite BaSrCo2Fe11AlO22 (BSCoFAO), which was reported to exhibit spin-driven ferroelectricity at room temperature. By means of magnetization, electric polarization, and neutron-diffraction measurements using single-crystal samples, we establish a H-T magnetic phase diagram for magnetic field perpendicular to the c axis (H⟂c). This system exhibits an alternating longitudinal conical (ALC) magnetic structure in the ground state, and it turns into a non-co-planar commensurate magnetic order with spin-driven ferroelectricity under H⟂c. The field-induced ferroelectric phase remains as a metastable state after removing magnetic field below 250 K. This metastability is the key to understanding of magnetic field reversal of the spin-driven electric polarization in this system. Inelastic polarized neutron-scattering measurements in the ALC phase reveal a magnetic excitation at around 7.5 meV, which is attributed to spin components oscillating in a plane perpendicular to the cone axis. This phasonlike excitation is expected to be an electric-field active magnon, i.e., electromagnon excitation, in terms of the magnetostriction mechanism.
 [1] ;  [2] ;  [3] ;  [3] ;  [4] ;  [5] ;  [1] ;  [1] ;  [2]
  1. RIKEN Center for Emergent Matter Science, Saitama (Japan)
  2. RIKEN Center for Emergent Matter Science, Saitama (Japan); Univ. of Tokyo, Kashiwa (Japan)
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); The Univ. of Tennessee, Knoxville, TN (United States)
  5. RIKEN Center for Emergent Matter Science, Saitama (Japan); Japan Atomic Energy Agency, Ibaraki (Japan); Comprehensive Research Organization for Science and Society, Ibaraki (Japan)
Publication Date:
OSTI Identifier:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 94; Journal Issue: 19; Journal ID: ISSN 2469-9950
American Physical Society (APS)
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). High Flux Isotope Reactor (HFIR)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States