Large Inverse Magnetocaloric Effects and Giant Magnetoresistance in Ni-Mn-Cr-Sn Heusler Alloys

The magnetostructural transitions, magnetocaloric effects, and magnetoresistance properties of Ni45Mn43CrSn11 Heusler alloys were investigated using X-ray diffraction (XRD), field-dependent magnetization, and electrical resistivity measurements. A large inverse and direct magnetocaloric effect has been observed in Ni45Mn43CrSn11 across the martensitic and Curie transition temperature, respectively. The values of the latent heat (L = 15.5 J/g) and corresponding magnetic (Delta S-M) and total (Delta S-T) entropy changes (Delta S-M = 35 J/Kg.K for Delta H = 5T and Delta S-T = 39.7 J/kg.K) have been evaluated using magnetic and differential scanning calorimetry (DSC) measurements, respectively. A substantial jump in resistivity was observed across the martensitic transformation. A large negative magnetoresistance (similar to 67%) was obtained at the magnetostructural transition for a field change of 5 T. The roles of the magnetic and structural changes on the transition temperatures and the potential application of Ni45Mn43CrSn11 Heusler alloys for refrigerator technology are discussed.