Explicit and closed-form expressions for describing magnetic behaviors of uniaxial anisotropy materials

We present explicit, analytic, and closed-form expressions for describing m agnetic behaviors of materials having the magnetic anisotropy energy of K s in(2) theta. The functional forms of the expressions depend on the ratio of an applied field to an anisotropy field and the ratio of the lowest critic al field, for a domain wall to nucleate or move, to the anisotropy field. T he present expressions for functions of experimentally measurable quantitie s gave an elegant method of fitting the quantities to the torque measuremen t. Furthermore, they may be useful to analyze the ferromagnetic resonance e xperiment and to measure the distribution of magnetic properties of magneti c aggregates. (C) 2000 American Institute of Physics. [S0003- 6951(00)00104 -2].