The Influence of Non-Magnetic Substrate on Spatial Distribution of Gaussian Fluctuations of Molecular Field in Magnetic Nanoparticles and Ultrathin Films
R. Łosiński and Z. Onyszkiewicz
Institute of Physics, A. Mickiewicz University, Umultowska 85, 61-614 Poznań, Poland
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An Ising (s=1) model of ferromagnetic nanoparticles and ultrathin films of the sc structure deposited on a non-magnetic substrate is considered. The substrate was assumed to affect the crystal field around the atoms lying closest to it. Consequently, the one-ion anisotropy constant of spin moments of these atoms becomes dependent on the appropriate component of the tensor of the magnetic structure deformation. This dependence was assumed to be linear. To obtain approximations of the Gaussian fluctuations of molecular field, the generalised equilibrium reduced density operator, along with the Feynman diagram technique were used. As a result, temperature dependences of the spatial distributions of mean fluctuations of the magnetic field versus the changes in the one-ion anisotropy constant induced by the non-magnetic substrate were obtained.
DOI: 10.12693/APhysPolA.97.955
PACS numbers: 75.10.Hk, 75.70.-i