The relationship between the dynamic remanent coercivity and the viscosity and irreversible susceptibility in magnetic media

It has been established previously that thermal switching in high density magnetic media causes a significant time dependence of the coercivity at least for times >10^-8 s. Here, the classical Arrhenius-Neel model assuming coherent rotation is applied to systems with distributions in volume, anisotropy and orientation and the numerical results for the time dependent remanent coercivity H_CR(t), the viscosity S_R, and the irreversible susceptibility, χ_IRR compared to new experimental data on CrO₂ particulate tapes with varying orientation. The results for an anisotropy distribution are significantly different from a volume distribution and are in better agreement with the data. All distributions produce Sharrock type behavior for H_CR(t), regardless of the distribution width. The model predicts that increasing the orientation distribution width will have very little effect on the fractional time dependence of H_CR, in agreement with experiment which showed that S_RχIRR/ and H_CR(t) were essentially independent of orientation. Finally, the direct connection between S_RχIRR/ and H_CR(t) is confirmed theoretically and experimentally.