Use of rotational transverse magnetometry to measure anisotropy energy

Rotational transverse magnetometry (RTM) is used to measure the anisotropy field of magnetic thin films. Magnetization reversal during rotation of a t wo-dimensional isotropic sample in an applied field is discussed. The relat ion between the transverse magnetization M-y and the applied field H is sol ved numerically. An excellent approximation for the transverse magnetizatio n is M-y/M-s = A(1-H/H-k)(2.5), where A = 1.1434, and H-k is the anisotropy field. For curve fitting to experimental data, both A and H-k were used as fitting parameters. Comparison between a constructed torque hysteresis met hod and this vibrating sample magnetometer (VSM) RTM method is made theoret ically and experimentally. Both results show that the VSM RTM will give a g ood extrapolation of the anisotropy field, whereas the torque measurement w ill slightly overestimate it. Anisotropy energy is calculated based on the anisotropy field and saturation magnetization for magnetic thin films. (C) 1999 American Institute of Physics. [S0021-8979(99)29508-4].