ON THE COERCIVE FORCE AND EFFECTIVE ACTIVATION VOLUME IN MAGNETIC-MATERIALS

The relationships between lg H(c) and lg upsilon-1 for the strong domain wall pinning model, the localized weak domain wall pinning model, unpinning (nucleation) of domain walls and uniaxial single domain particles have been deduced, which can be written as, lg H(c) = lg upsilon-1 + F(i)(T...), where H(c) is the coercive force, upsilon is the activation volume, F(i)(T...) is a complex function which has different forms for different models. Values of F(i)(T...) for different models have been calculated. The calculated results showed that F(i)(T...) is approximately a constant with the average value -13.91 at room temperature. Therefore lg H(c) is linearly proportional to lg upsilon-1 for different materials at room temperature, which has been proved by experiments.