Investigation of martensitic transformation and magnetoresistance properties of cu-substituted Ni-Mn-Sn-B melt spun ribbons

Ni-50-xCu(x)Mn(38)Sn(12) + B3% at (x = 0, 1, 3 and 5) melt spun ribbons have been fabricated by melt spinning technique. Structural, electrical and magnetoresistance properties of the ribbons were investigated in this study. It was identified that the austenite phase with the L2(1) type structure was formed in the ribbons, regardless of composition. Temperature dependence of resistance measurements exhibited the first order martensite transition in the ribbons. The largest negative magnetoresistance (similar to 55%) was obtained at 262 K in the RB1 ribbon. Depending on the Cu-content and magnetic field, a noticeable shift of martensite transition temperature to low temperatures has been clearly observed. From magnetic field dependence of the resistance, it was seen that the resistances dropped sharply with the increase of the applied magnetic field and overlapped near 80 kOe, regardless of temperatures, which strongly indicates the magnetic field-induced martensite-austenite transition.