MAGNETIC-PROPERTIES OF THE PREMARTENSITIC TRANSITION IN NI2MNGA ALLOYS

Magnetization as a function of field and temperature for a ferromagnet ic Heusler alloy Ni2MnGa is reported. Magnetization above the Martensi tic transition displays a field-dependent peak effect, a direct magnet ic evidence of premartensitic phase. At low fields, the peak effect oc curs at a temperature consistent with the observations of the micromod ulated structure transition seen from neutron scattering, electron mic roscopy, and ultrasonic studies in this compound. At high fields, the peak effect is suppressed. The strong field dependence of the peak tem perature suggests a large magnetoelastic interaction in the intermedia te phase. [S0163-1829(98)09537-X].