Magnetic hard nanocrystalline MnBi has been prepared by melt spinning and subsequent
low temperature annealing. A coercivity of 2.5 T can be achieved at 540 K for MnBi with an
average grain size of about 20-30 nm. The coercivity iH c, mainly controlled by the coherent
magnetization rotation, shows a strong dependence on the time of grinding and exhibits a
positive temperature coefficient from 100 up to 540 K. The unique temperature dependent
behavior of the coercivity (magnetocrystalline anisotropy) has a relationship with the …