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

Sudip Pandey,Dipanjan Mazumdar,Anil Aryal,Naushad Ali,Abdiel Quetz,Shane Stadler,Igor Dubenko

doi:10.3390/magnetochemistry3010003

Abstract

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 (ΔSM) and total (∆ST) entropy changes (ΔSM = 35 J/kg·K for ΔH = 5T and ∆ST = 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 (~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.

Highlights

Magnetic materials with large magnetic entropy changes (∆SM) are potential candidates for use in new refrigerator technology [1]
Large ∆SM values have been observed for a materials showing first order transitions (FOT) in which sharp changes of magnetization occur across the ordering temperature with simultaneous changes in magnetic and structural phases [2,3]
The advantage of using materials with a large ∆SM at the second order transitions (SOT) is the complete reversibility of the magnetization process

Summary

Introduction

Magnetic materials with large magnetic entropy changes (∆SM) are potential candidates for use in new refrigerator technology [1]. Large ∆SM values have been observed for a materials showing first order transitions (FOT) in which sharp changes of magnetization occur across the ordering temperature with simultaneous changes in magnetic and structural phases [2,3]. These materials are characterized by a sharp peak in ∆SM in a relatively narrow temperature range. Materials undergoing second order transitions (SOT) exhibit relatively small values of ∆SM over wide working temperature intervals [4,5]. Magnetic refrigerant materials that exhibit both magnetic entropy changes can be used in a refrigeration cycle that exploits both effects [6,7]

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