Effect of high magnetic field on the two-step martensitic-phase transition in Ni₂MnGa

Using a low-temperature x-ray diffraction apparatus in a high field, a systematic study was performed of the stoichiometric Ni₂MnGa alloys in a wide temperature range from 10 K to room temperature and in fields up to 5 T. X-ray diffraction data at different fields clearly show the martensitic-phase transition is a two-step process. It is found that the martensitic-transition temperature T_m increases and the premartensitic-transition temperature T_p decreases with increasing magnetic fields up to 2 T, and then both remain unchanged in fields up to 5 T.