The Coercivity of Particle Arrays
Journal
Journal of Applied Physics
Journal Volume
73
Journal Issue
10
Pages
6662-6664
Date Issued
1993
Author(s)
Abstract
Thermal effects in an array of nonidentical, noninteracting single domain ferromagnetic particles are studied. Two sources of stochasticity are recognized within the array: the intrinsic stochastic nature of thermal relaxation and variations within the particles�� volume and orientation with respect to applied field, both are discussed in turn. We use the log-normal volume distribution {��(�mV)?1exp[?ln2(V/V0)/(2�m2)]} and a cos�h �r angular distribution to calculate the mean coercivity B?c of a particle array. We find that B?c increases rapidly with increasing average volume <V?=V0 exp(�m2/2) while for misaligned particles (�h?��) we observe a sudden decrease in B?c accompanied by a gradual loss of frequency dependence.
Type
journal article