Pressure induced martensitic transition, magnetocaloric and magneto-transport properties in Mn-Ni-Sn Heusler alloy

Abstract

In this work, we report the effect of hydrostatic pressure (P) on the martensitic transition in Mn50Ni40Sn10 Heusler alloy using the magnetization and electrical resistivity measurements. Martensitic transition temperature (T-M) is found to shift significantly to higher temperatures with the application of pressure, which reflects the stabilization of the martensite phase. On the other hand, T-M shifts to lower temperatures with magnetic field, which implies the stabilization of the austenite phase. The estimated rate of change of martensitic transition temperature with pressure (dT(M)/dP) for the present alloy is similar to 4.6 K/kbar. The alloy shows a maximum negative magnetoresistance (MR) of 9.6% for P = 4 kbar at the martensitic transition. A large isothermal magnetic entropy change (Delta S-M) of 16.6 J/kg.K and a refrigerant capacity (RC) of similar to 146 J/kg are observed at TM under ambient pressure. Both quantities are found to decrease with the increase of pressure. The values of Delta S-M and adiabatic temperature change (Delta T-ad), calculated from heat capacity measurements are similar to 11.3 J/kg. K and -3.4 K respectively for 50 kOe field change. The observed pressure and field dependence results have been explained using the Clausius-Clapeyron equation. The combined effect of pressure and field on the martensitic transition is also discussed.