Magnetic phase transition of MnBi under high magnetic fields and high temperature

Abstract

Magnetization measurements and differential thermal analysis (DTA) of poly crystalline MnBi were carried out in magnetic fields up to 14 T and in 300-773 K, in order to investigate the magnetic phase transition. The magnetic phase transition temperature (Tt) at a zero magnetic field is 628 K and linearly increases with increasing fields up to 14 T at the rate of 2 KT- '. A metamagnetic transition between the paramagnetic and field-induced ferromagnetic states was observed just above Tt. The exothermic and endothermic peaks were detected in the magnetic field dependence of DTA signals in 626-623 K, which relates to the metamagnetic transition. The obtained results were discussed on the basis of a mean field theory. © 2007 The Japan Institute of Metals.