Effect of Magnetic Interaction on Thermally Activated Reversal in a Magnet With a Distribution of Energy Barriers

The time dependence of magnetization is usually expressed as M(t)=M0-SInt [see Proc. Phys. Soc. 62, 562 (1949)] for magnetic viscosity experiments. Considering magnetic interaction during the thermal activation process, a form as M(t)=M0-SIn(t+t0) is deduced. The dipolar interaction and exchange coupling in a magnet can lead to positive and nonpositive t0, respectively. In the experiments of the magnetic viscosity for nanocrystalline Pr2Fe14B ribbons, the existence of positive t0 is confirmed.