Generalized torque analysis of magnetic uniaxial anisotropy

A method for analyzing uniaxial torque data has been developed. The analysis provides a reliable method of finding the magnetization, first- and second-order uniaxial anisotropy constants, and associated confidence intervals. Based on the well-known 45°C method, the technique analyzes data taken at any angle and provides for determination of K₂ in addition to M and K₁. Constant angle torque data is fit to a uniaxial model via a least squares method at many angles, wherein each angle data set provides an independent measure of M, K₁, and K₂. Mean values and uncertainties are obtained by combining results from all angles. The procedure was tested on simulated torque data generated from known M , K₁, and K₂ values with subsequent introduction of normal distributed noise and a Fe/Cu multilayer sample. Confidence intervals associated with the extracted values are also presented