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Temperature dependence of magnetic anisotropy of germanium/cobalt cosubstituted cobalt ferrite
Journal of Applied Physics (2009)
  • N. Ranvah, Cardiff University
  • Y. Melikhov, Cardiff University
  • Ikenna C. Nlebedim, Cardiff University
  • David C. Jiles, Cardiff University
  • J. E. Snyder, Cardiff University
  • A. J. Moses, Cardiff University
  • P. I. Williams, Cardiff University
The variations in magnetization and magnetic anisotropy of Ge4+/Co2+ cosubstituted cobaltferrite with temperature were investigated for a series of compositions Co1+xGexFe2−2xO4 (0≤x≤0.4). The magnetization at 5 T and low temperature were observed to increase for all Ge/Co cosubstituted samples compared to pure CoFe2O4. Hysteresis loops were measured for each sample over the magnetic field range of −5 T to +5 T for temperatures in the range of 10–400 K. The high field regions of these loops were modeled using Law of Approach to saturation, which represents the rotational and forced magnetization processes. The first order cubic magnetocrystalline anisotropy coefficient K1 was calculated from these fits. K1 decreased with increasing Ge content at all temperatures. Anisotropy increased substantially as temperature decreased. Below 150 K, for certain compositions (x=0, 0.1, 0.2, and 0.3), the maximum applied field of μ0H=5 T was less than the anisotropy field and therefore insufficient to saturate the magnetization. In these cases, the use of the Law of Approach model can give values of K1 that are lower than the correct values and this method cannot be used to estimate anisotropy accurately under these conditions.
  • Germanium,
  • Magnetic anisotropy,
  • Cobalt,
  • Ferrites,
  • Saturation moments
Publication Date
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Copyright 2009 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Journal of Applied Physics 105 (2009): 07A518 and may be found at
Citation Information
N. Ranvah, Y. Melikhov, Ikenna C. Nlebedim, David C. Jiles, et al.. "Temperature dependence of magnetic anisotropy of germanium/cobalt cosubstituted cobalt ferrite" Journal of Applied Physics Vol. 105 Iss. 7 (2009)
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