Effect of the second-order anistropy constant on the transverse susceptibility of uniaxial ferromagnets

A generalized theoretical approach of the transverse susceptibility, χT, in the case of uniaxial ferromagnets is presented. This advances the classical model of transverse susceptibility where only the first-order anisotropy constant, K1, is taken into account and makes possible the study of the influence of the second-order anisotropy constant, K2 on the χT curves. It is shown that additional Barkhausen jumps driven by higher-order anisotropy constants emerge more evidently in the field dependence of χT making their detection much easier than from the hysteresis loop. Based on the obtained results, we propose a simple method to determine both, K1 and K2 independently from χT experiments.