Anomalous Field Dependence of Magnetic Anisotropy Constant of Mn Alloy

Abstract

A single crystal of the ordered phase of ${\mathrm{Au}}_4\mathrm{Mn}$ was prepared by the Bridgeman and annealing methods. The magnetic anisotropy of ordered ${\mathrm{Au}}_4\mathrm{Mn}$ was measured by the torque method utilizing this crystal below the Curie temperature. The magnetic easy direction was determined to be the tetragonal 〈001〉 axis. The four‐fold torque amplitude first increases and then decreases with increasing field strength. This behavior can be understood as an effect of the twin structured model of the ordered ${\mathrm{Au}}_4\mathrm{Mn}$ . The uniaxial anisotropic energy at absolute zero was determined to be ${\text{3.0\hspace{0.17em}×\hspace{0.17em}10}}^6\hspace{0.17em}\mathrm{erg/cc}$ .