The phase transitions, magnetocaloric effect, and magnetoresistance in Co doped Ni–Mn–Sb ferromagnetic shape memory alloys

Abstract

The phase transitions, magnetocaloric effect, and magnetoresistance in Ni50−xCoxMn39Sb11 (x=0–11) ferromagnetic shape memory alloys were investigated. The temperatures of martensitic transformation and magnetic transition in austenitic phase depend strongly on the Co concentration, while the magnetic transition temperature in martensitic phase shows small dependence on alloy composition. For 7≤x≤9, the martensitic transformation is accompanied by a sudden change in magnetization. Large positive magnetic entropy changes and negative magnetoresistance near room temperature, which originate from the magnetic-field-induced transformation from the weak-magnetic high-resistance martensitic phase to the ferromagnetic low-resistance parent phase, are observed in these alloys. Our results indicate the potential application of Ni50−xCoxMn39Sb11 alloys in magnetic refrigeration and magnetic sensors.