The study of low-field positive and negative magnetic entropy changes in Ni43Mn46-xCuxSn11 alloys

A series of Ni43Mn46-xCuxSn11 (x=1, 2, and 3) alloys was prepared by the arc melting method. The martensitic transition shifts to a higher temperature with increasing Cu concentration. The isothermal magnetization curves around the martensitic transition temperature show a typical metamagnetic behavior. Under a low applied magnetic field of 10 kOe, positive values of magnetic entropy change around the martensitic transition temperature are 14.1, 18.0, and 15.8 J/kg K for x=1, 2, and 3, respectively. While in the vicinity of the Curie temperature of the austenitic phase, these negative values are 1.1, 1.0, and 0.9 J/kg K for x=1, 2, and 3, respectively. The origin of the large entropy changes and the potential application for Ni43Mn46-xCuxSn11 alloys as a working substance for magnetic refrigeration are discussed. (c) 2007 American Institute of Physics.