Martensitic phase transformations and magnetocaloric effect in Al co-sputtered Ni-Mn-Sb alloy thin films

We systematically investigated the influence of aluminium (Al) content on the martensitic transformations and magnetocaloric effect (MCE) in Ni-Mn-Sb ferromagnetic shape memory alloy (FSMA) thin films. The temperature-dependent magnetization (M-T) and resistance (R-T) results displayed a monotonic increase in martensitic transformation temperature (TM) with increasing Al content. From the isothermal magnetization (M-H) curves, a large magnetic entropy change (ΔSM) of 23 mJ/cm3 K was observed in N49.8Mn32.97Al4.43Sb12.8. A remarkable enhancement of MCE could be attributed to the significant change in the magnetization of Ni-Mn-Sb films with increasing Al content. Furthermore, a high refrigerant capacity (RC) was observed in Ni-Mn-Sb-Al thin films as compared to pure Ni-Mn-Sb. The substitution of Al for Mn in Ni-Mn-Sb thin films with field induced MCE are potential candidates for micro length scale magnetic refrigeration applications where low magnetic fields are desirable.