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Title: Magnetic and structural properties of ferromagnetic Fe5PB2 and Fe5SiB2 and effects of Co and Mn substitutions

Crystallographic and magnetic properties of Fe5PB2, Fe4CoPB2, Fe4MnPB2, Fe5SiB2, Fe4CoSiB2, and Fe4MnSiB2 are reported. All adopt the tetragonal Cr5B3 structure-type and are ferromagnetic at room temperature with easy axis of magnetization along the c-axis. The spin reorientation in Fe5SiB2 is observed as an anomaly in the magnetization near 170 K, and is suppressed by substitution of Co or Mn for Fe. The silicides are found to generally have larger magnetic moments than the phosphides, but the data suggests smaller magnetic anisotropy in the silicides. Cobalt substitution reduces the Curie temperatures by more than 100 K and ordered magnetic moments by 16-20%, while manganese substitution has a much smaller effect. This suggests Mn moments align ferromagnetically with the Fe and that Co does not have an ordered moment in these structures. Anisotropic thermal expansion is observed in Fe5PB2 and Fe5SiB2, with negative thermal expansion seen along the c-axis of Fe5SiB2. First principles calculations of the magnetic properties of Fe5SiB2 and Fe4MnSiB2 are reported. The results, including the magnetic moment and anisotropy, and are in good agreement with experiment.
 [1] ;  [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Journal of Applied Physics
Additional Journal Information:
Journal Volume: 118; Journal Issue: 16; Journal ID: ISSN 0021-8979
American Institute of Physics (AIP)
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Critical Materials Institute (CMI)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
Country of Publication:
United States
OSTI Identifier: