磁场诱导制备Bi-Mn合金的结构和低温磁性研究

系统研究了在外加诱导磁场下制备的Bi-Mn 6%合金的结构和低温磁特性.结果表明,在外加诱导磁场下制备的Bi-Mn 6%合金呈现典型的双相结构和各向异性特征,MnBi相c轴沿外加诱导磁场方向定向排列.发现MnBi相的矫顽力随温度的升高而增大,而饱和磁化强度则随温度的升高而减小.MnBi相的自旋重定向温度TSR随测量磁场的增大逐渐向低温区移动,在高的外加测量磁场下这种自旋重定向特征消失,发现了TSR随外加诱导制备磁场的增大而逐渐向高温区移动.对磁场诱导制备织构化MnBi相和该类材料磁各向异性能的物理机制进行了分析和讨论.

STUDY OF STRUCTURE AND MAGNETIC PROPERTIES AT LOW-TEMPERATURE FOR Bi-Mn ALLOYS FABRICATED BY MAGNETIC FIELD INDUCEMENT

The Bi Mn wt6% alloys are solidified from semi solid state in a magnetic field. The microstructure and magnetic properties have been studied systematically at low temperature. The results show that the samples are eutectic system of double phase and have large anisotropy. It was shown that alignment of MnBi crystals along the applied field occurred. Magnetic measurements show c axis of MnBi is parallel to the applied field. The coercivity increases with the increasing temperature and exhibits a positive temperature coefficient; but the saturation magnetization decreases with the increasing temperature. The spin reorientation temperature T SR for MnBi alloys decreases with increasing measure magnetic field and the peak shape becomes wide. When the magnetic field increases to above 1T, the spin reorientation phenomena vanish in the present experiment. The characteristic temperature T SR increases with the increasing induced magnetic field.