Magnetization time decay in CrO2 tape

Measurements are reported of the bulk saturation magnetization, the coercive field, and the rate of magnetization decay per decade of time of IBM 3480 CrO₂ tape over the temperature range 1.6 K <T<400 K. The extension of the data down to 1.6 K reveals that the decay rate extrapolates to zero as T approaches 0 K, with approximately a T^1/2 dependence on temperature, as predicted by S.H. Charap´s (1988) model of thermal activation. A comparison of the data with the theory over the entire temperature range suggests that while the theory provides a qualitative framework for interpretation, a detailed evaluation of the model parameters will likely require appropriate extension to include realistic sample particle distributions of volume and orientation, as well as the relative contribution of shape and crystalline anisotropy