Combined effect of hydrostatic pressure and magnetic field on the martensitic transition in the Ni49CuMn34In16alloy

Abstract

The combined effect of hydrostatic pressure and magnetic field on the martensitic transition in the Ni${}_{49}$CuMn${}_{34}$In${}_{16}$ alloy is investigated through a study of electrical resistivity. It is shown that a combination of an external pressure of 2 kbar and a magnetic field of 20 kOe can produce a magnetoresistance (MR) of \ensuremath{\sim}24% in the Ni${}_{49}$CuMn${}_{34}$In${}_{16}$ alloy at the ambient temperature of 296.5 K. The volume change in the alloy across the austenite-to-martensite phase transition is estimated to be \ensuremath{\sim}0.4%, which shows the potential of the alloy in near room-temperature actuator applications. The phase diagrams depicting the detailed field and pressure dependence of the characteristic temperatures associated with austenite-martensite phase transition are constructed from the experimental data. The results indicate that the strain fields produced in the Ni${}_{49}$CuMn${}_{34}$In${}_{16}$ alloy are different when the alloy is cooled under externally applied pressure from what they are when the alloy is cooled in ambient pressure. These changed strain fields appear to influence the scattering of conduction electrons and the dynamics of the austenite-to-martensite phase transition in the alloy in the presence of external pressure. The present results may be useful for finding a guideline for generating chemical pressure (obtained through the partial substitution of atoms in the system) leading to newer NiMnIn alloys with room temperature functional properties.