Wt. Coffey et al., EXACT ANALYTIC FORMULAS FOR THE CORRELATION TIMES FOR SINGLE-DOMAIN FERROMAGNETIC PARTICLES, Journal of magnetism and magnetic materials, 127(3), 1993, pp. 120000254-120000260
Exact solutions for the longitudinal relaxation time T-parallel to and
the complex susceptibility x(parallel to)(omega) of a thermally agita
ted single domain ferromagnetic particle are presented for the simple
uniaxial (Maier-Saupe) potential of the crystalline anisotropy conside
red by Brown [Phys. Rev.130 (1963) 1677].