Fabrication, Structural and Magnetic Properties for Aligned MnBi

MnBi compound is fabricated under a magnetic field of 1 T, and the c-axis of hexagonal MnBi crystal is aligned parallel to the magnetic field direction. The saturation magnetization M_s decreases with the increase of temperature. At temperatures below 200 K, the coercive field H_c is about 150 Oe, while the coercive field H_c increases with temperature above 200 K. From 200 K to 300 K, the remnant magnetization M_r and the M_r/M_s increase with the temperature. Below 200 K, M_r and M_r/M_s reach roughly a constant value. However, there is an abnormal increase at 100 K in H_c, M_r and M_r/M_s, which comes from a spin-reorientation in MnBi. Magnetization results show the spin-reorientation for MnBi at about 91 K due to the variations of the anisotropy constants.