Thin Solid Films, Vol.518, No.21, 6087-6092, 2010
Effect of a randomly oriented field on superparamagnetic ultrafine particles
The effect of a constant and a randomly oriented magnetic field H(psi, phi), on the Neel relaxation time tau, of an assembly of ultrafine ferromagnetic particles with uniaxial anisotropy. is investigated In this regard, the smallest non-vanishing eigenvalue of the Fokker-Planck equation is calculated as a function of psi, phi and the parameter h = M(s)vH/k(B)T, where M(s) and v are denoting the saturation magnetization and the volume of a particle, respectively. The results obtained bring noticeable changes compared to previous calculations, and give satisfactory interpretation of the relaxation phenomenon in such systems. (C) 2010 Elsevier B.V. All rights reserved