Large magnetocaloric and magnetoresistance effects during martensitic transformation in Heusler-type Ni44Co6Mn37In13 alloy

Abstract

NiMn-based Heusler alloys are promising materials in the multi-functional applications due to their ample magneto-responsive effects across martensitic transformation, such as magnetocaloric effect, magnetostriction and magnetoresistance. In this work, the evolution of microstructure, large magnetocaloric and magnetoresistance effects during martensitic transformation are systematically studied in a Ni44Co6Mn37In13 alloy. Magnetic and caloric measurements verify that the martensite in weak magnetic state would gradually transform to be ferromagnetic austenite upon heating. The temperature dependence of microstructure observed in an in-situ optical microscopy unambiguously verify the ‘kinetic arrest’ of martensitic transformation. Most importantly, due to the high sensitivity of transformation to the magnetic field, large magnetocaloric and magnetoresistance effects near room temperature are obtained, including magnetic entropy changes of 8.4 Jkg-1K−1, effective refrigerant capacity of 181 Jkg−1 and magnetoresistance change of 75 % under the field change of Δμ0H = 0–5 T, making the studied sample promising for room temperature magnetic refrigeration and magnetic storage.