Temperature Dependence Of Magnetic Viscosity And Irreversible Susceptibility For Aligned Stoner-Wohlfarth Particle

The temperature dependence of the magnetic viscosity S and the irreversible susceptibility chi(irr) has been calculated for distributions of noninteracting, aligned Stoner-Wohlfarth particles. Significant differences are shown to exist for volume and anisotropy field distributions. For a volume distribution, S-max is independent of temperature and chi(irr,max) similar to T-1/2, below the superparamagnetic temperature. For an anisotropy field distribution S-max approximate to c(1)T(1/2) + c(2)T and chi(irr,max) approximate to c(3) + c(4)S(max), where the c's are positive constants. Results obtained using approximate analytical expressions that have been previously published have been compared with numerical calculations. (C) 2000 American Institute of Physics. [S0021-8979(00)44808-5].