COMPLEX MAGNETIC-SUSCEPTIBILITY OF UNIAXIAL SUPERPARAMAGNETIC PARTICLES IN A STRONG STATIC MAGNETIC-FIELD

The magnetic relaxation of a system of single-domain ferromagnetic par ticles in the presence of a strong static magnetic field directed at a n arbitrary angle relative to the particle anisotropy axis is investig ated. A system of linear difference-differential equations for the mom ents (averaged spherical harmonics! is derived without recourse to the Fokker-Planck equation by averaging Gilbert's equations with a fluctu ating field. An exact solution (in terms of matrix continuous fraction s) is found for this system. The relaxation times and spectra of the c omplex magnetic susceptibility are calculated. (C) 1998 American Insti tute of Physics. [S1063-7834(98)01709-2].