Nonanaliticity of the Magnetization Curve: Application to the Measurement of Anisotropy in Polycrystalline Samples

Abstract

We studied the second derivative of the magnetization with respect to the magnetic field, $\frac{{d}^{2}M}{d{H}^{2}}$, for polycrystalline materials having uniaxial anisotropy. Evidence is given of a singular point located at $H={H}_{A}$, the anisotropy field. The observed sharp peak is associated with the infinity at $H={H}_{A}$ of the $\frac{{d}^{2}M}{d{H}^{2}}$ curve for the single crystal in the hard direction. The detection of singularities is proposed as a new, and sometimes unique, method of measuring magnetic anisotropy using polycrystalline samples.