Magnetic anisotropy properties and spin reorientation for textured Bi-Mn alloys fabricated by a field-inducing technique

摘要

By a magnetic-field-inducing technique, Bi-Mn alloys were fabricated with the textured structure and an-isotropic characteristics. Magnetic properties of MnBi compound aligned in alloys with 6 wt% Mn have been investigated systematically. The saturation magnetization M_s decreases with the increase of temperature. At temperatures below 150 K, the coercive field H_c decreases with the increase of temperature, while the coercive field H_c increases with temperature above 150 K. In the range of temperature from 150 to 300 K, the remanent magnetization M_r and the M_r/M_s increase with the temperature, while below 150 K, the M_r and the M_r/M_s reach a constant value of nearly zero. The magnetic moments rotated from being parallel to the c axis toward the basal plane for MnBi (the low-temperature phase) at about 90 K. Most of all, under a dc magnetic field applied parallel to the c axis, the transition temperature of the spin reorientation decreases with the increase of magnetic field, and even decreases 30 K under 5 T. The mechanism of the spin-reorientation transition and the change of its transition temperature are discussed and explained by phenomenological theory.