Effects of interaction of nanoparticles in a highly anisotropic ferrimagnet |
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Authors: | L P Ol’khovik Z I Sizova E V Shurinova and A S Kamzin |
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Institution: | 1.Karazin Kharkiv National University,Kharkiv,Ukraine;2.Ioffe Physical-Technical Institute,Russian Academy of Sciences,St. Petersburg,Russia |
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Abstract: | This paper reports on a study of the field and temperature dependences of the parameters of the particle magnetic interaction
in a densely packed system of nanocrystals of the highly anisotropic hexagonal ferrite BaFe12O19 with the particles distributed in diameter within the range 10—100 nm and having volumes satisfying the criterion of “small
Stoner—Wohlfarth particles.” It is shown that the resultant particle interaction in the temperature range 300 K≤T≤640 K has a negative sign, whereas for T>640 K, it is positive. The maximum values of the parameter Δm allow classification of the interaction as moderate in strength. The temperature dependences of the interaction parameters
are found to correlate with manifestation of the size and surface effects in the system, which are characteristic of small
particles (transition to the superparamagnetic state, “surface” anisotropy, and reduced exchange interaction in a structurally
defective near-surface layer of particles). |
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