AIP Advances (May 2017)

Magnetic anisotropy in spherical Fe16N2 core–shell nanoparticles determined by torque measurements

  • Eiji Kita,
  • Kenichi Shibata,
  • Yuji Sasaki,
  • Mikio Kishimoto,
  • Hideto Yanagihara

DOI
https://doi.org/10.1063/1.4974276
Journal volume & issue
Vol. 7, no. 5
pp. 056212 – 056212-5

Abstract

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The magnetic anisotropy energy for core–shell α”-Fe16N2 nanoparticles was evaluated by the rotational hysteresis loss obtained from magnetic torque measurements. The saturation magnetization of the α”-Fe16N2 core was deduced from volume fractions of α”-Fe16N2 determined by an analysis of a low-temperature Mossbauer spectrum. The saturation magnetization and the anisotropy energy were found to be 234 emu/cc and 6.9 Merg/cm3, respectively. These values coincide with those of bulk-like single-phase α”-Fe16N2 particles. This crystalline anisotropy is still smaller than the shape anisotropy of the thin films (2πMs2=20 Merg/cm3), and a perpendicular magnetic state is not expected for the thin-film form.