Multi-field synergistic regulation enhanced multicaloric effect in all-d-metal Ni37Co13Mn35Ti15 alloy

Solid-state cooling technology has attracted great attention to replace traditional vapor-compression cooling technology due to its advantages of environmentally friendly, energy conservation, and high efficiency. However, the cooling performance of a single field (magnetic, stress or electric field) induced caloric effect is still insufficient. Recently, a larger multicaloric effect is expected to be achieved by the synergistic regulation of multiple fields. In this study, we choose all-d-metal Ni37Co13Mn35Ti15 alloy with magnetostructural phase transition and systematically study the multicaloric effect through the synergistic regulation of external stress and magnetic fields based on our homemade multicaloric effect testing device. The magnetic field and stress field play opposite effects on the phase transition, thus contributing contradictory caloric effect to multicaloric effect. By loading stress without magnetic field while unloading stress under magnetic field of 1.1 T, the stress hysteresis and energy hysteresis loss can be reduced by up to 45.2% and 54.8% in comparison with those obtained from a non-ideal regulation protocol. Moreover, the maximum adiabatic temperature change |ΔTad| during unloading increases by 24% from 6.3 K to 7.8 K with the application of magnetic field (1.1 T), suggesting a larger multicaloric effect than that of a single elastocaloric effect. These results prove that multi-field synergistic regulation is an effective means to enhance the multicaloric effect and reduce the hysteresis and energy loss of materials with the magnetostructural transition.