Dynamic magnetization of epsilon-Fe2O3 in pulse field: Evidence of surface effect

Тип публикации: статья из журнала

Год издания: 2015

Идентификатор DOI: 10.1063/1.4907586

Ключевые слова: Anisotropy, Magnetic materials, Magnetization, Nanomagnetics, Nanoparticles, Particle size, Dynamic magnetization, Magnetic behavior, Magnetization dynamics, Quasi-static conditions, Reference values, Superparamagnetic effect, Surface anisotropy, Surface contribution, Magnetic anisotropy

Аннотация: The magnetization dynamics of epsilon-Fe2O3 nanoparticles with an average size of about 9nm is investigated. From comparison of the hysteresis loops obtained in quasi-static conditions and under pulse fields with amplitudes up to 200 kOe and pulse lengths 8-32ms, it follows that the effective coercivity increases considerably with the variation rate of the imposed magnetic field. A theoretical explanation of this behavior is proposed. The model takes into account the superparamagnetic effects as well as the fact that magnetic anisotropy of the nanoparticles, along with the bulk term, includes a surface contribution. The latter, being of minor importance for the observed magnetic behavior of 25-100nm particles, becomes essential when the particle size is below 10 nm. From the experimental data, a reference value of the surface anisotropy of nanodisperse epsilon-Fe2O3 is established, and evidence is presented to the effect that below 300K this contribution does not significantly depend on temperature. (C) 2015 AIP Publishing LLC.

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Издание

Журнал: JOURNAL OF APPLIED PHYSICS

Выпуск журнала: Vol. 117, Is. 6

ISSN журнала: 00218979

Место издания: MELVILLE

Издатель: AMER INST PHYSICS

Авторы

  • Balaev D.A. (Siberian Federal University, Krasnoyarsk)
  • Bukhtiyarova G.A. (Boreskov Institute of Catalysis, Russian Academy of Sciences, Siberian Branch)
  • Martyanov O.N. (Boreskov Institute of Catalysis, Russian Academy of Sciences, Siberian Branch)
  • Shaikhutdinov K.A. (Kirensky Institute of Physics, Russian Academy of Sciences, Siberian Branch)
  • Dubrovskiy A.A. (Kirensky Institute of Physics, Russian Academy of Sciences, Siberian Branch)
  • Popkov S.I. (Kirensky Institute of Physics, Russian Academy of Sciences, Siberian Branch)
  • Balaev A.D. (Kirensky Institute of Physics, Russian Academy of Sciences, Siberian Branch)
  • Krasikov A.A. (Siberian Federal University, Krasnoyarsk)
  • Poperechny I.S. (Perm National Research Polytechnic University, Perm)
  • Raikher Y.L. (Ural Federal University, Ekaterinburg)
  • Yakushkin S.S. (Boreskov Institute of Catalysis, Russian Academy of Sciences, Siberian Branch)

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