Experimental study on coupled caloric effect driven by dual fields in metamagnetic Heusler alloy Ni50Mn35In15

Abstract

The multicaloric and coupled caloric effect of metamagnetic shape memory alloy Ni50Mn35In15 driven by hydrostatic pressure and magnetic field has been systematically investigated. The existence of pressure significantly changes the relationship between the magnetic volume coupling coefficient and temperature. Thermodynamic analysis indicates that the magnetocaloric effect at a certain pressure is equivalent to the magnetocaloric effect at ambient pressure adjusted by the coupled caloric effect (ΔScp). This theoretical result is verified by magnetic measurements under various pressures for the Ni50Mn35In15 with the inverse magnetocaloric effect. When a pressure of 0.995 GPa is applied, the peak value of entropy change can be as high as |ΔS| ∼ 25.7 J kg−1 K−1 upon a magnetic field change of 5–0 T, which increases by 8% compared to that of ambient pressure though the magnetization change (ΔM) across martensitic transition reduces 20% owing to the shift of the transition to higher temperature by 30 K. Detailed analysis indicates that the coupled caloric effect involving the strengthened magnetostructural coupling under pressure is responsible for the enhanced entropy change. The quantitative analysis of cross coupling term driven by dual fields reveals the essence of regulated magnetocaloric effect by pressure, which will be helpful for designing new materials based on the magnetostructural coupling strength.