Physics of the Solid State

, Volume 42, Issue 5, pp 918–924

Nonlinear response of superparamagnetic particles to a sudden change of a high constant magnetic field

Authors

  • Yu. P. Kalmykov
    • Institute of Radio Engineering and Electronics (Fryazino Branch)Russian Academy of Sciences
  • S. V. Titov
    • Institute of Radio Engineering and Electronics (Fryazino Branch)Russian Academy of Sciences
Magnetism and Ferroelectricity

DOI: 10.1134/1.1131312

Cite this article as:
Kalmykov, Y.P. & Titov, S.V. Phys. Solid State (2000) 42: 918. doi:10.1134/1.1131312

Abstract

For a system of superparamagnetic particles in a high external constant magnetic field, a technique for calculating the nonlinear response to a sudden change in the field direction and magnitude is proposed. A set of momentary equations for the averaged spherical harmonics, which is derived from the Fokker-Planck equation for the magnetization-orientation distribution function is the basis of this technique. As an example, the nonlinear response of a system of particles with anisotropy of the easy-axis type is examined. For this case, a solution to the momentary equations is obtained by using matrix continued fractions. The magnetization relaxation time and the spectrum of the relaxation function are calculated for typical values of anisotropy, dissipation, and nonlinearity parameters. It is shown that the magnetization kinetics is essentially dependent on these parameters.

Copyright information

© MAIK "Nauka/Interperiodica" 2000