Excess Ni-doping induced enhanced room temperature magneto-functionality in Ni-Mn-Sn based shape memory alloy
Present work reports on the observation of large magnetoresistance (∼-30% at 80 kOe) and magnetocaloric effect (∼12 J.kg-1.K-1 for 0-50 kOe) near room temperature (∼290 K) on the Ni-excess ferromagnetic shape memory alloy Ni2.04Mn1.4Sn0.56. The sample can be thought of being derived from the parent Ni2Mn1.4Sn0.6 alloy, where excess Ni was doped at the expense of Sn. Such Ni doping enhances the martensitic transition temperature and for the Ni2.04Mn1.4Sn0.56 it is found to be optimum (288 K). The doped alloy shows enhanced magneto-functional properties as well as reduced saturation magnetization as compared to the undoped counterpart at low temperature. A probable increment of antiferromagnetic correlation between Mn-atoms on Ni substitution can be accounted for the enhanced magneto-functional properties as well as reduction in saturation moment.