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

Abstract

Abstract 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.