Multicaloric effect in synergic magnetostructural phase transformation Ni-Mn-Ga-In alloys

Multicaloric effect refers to a thermal response of materials driven by more than one external field. In this work, using a self-designed multicaloric effect characterization setup, we directly measured the adiabatic temperature change ($\mathrm{\ensuremath{\Delta}}{T}_{\mathrm{ad}}$) under uniaxial stress and magnetic field for a spin-lattice synergic coupled system of Ni-Mn-Ga-In. Both stress and magnetic field favor the martensitic transformation. A large $\mathrm{\ensuremath{\Delta}}{T}_{\mathrm{ad}}$ of \ensuremath{-}6.7 K was achieved in the ${\mathrm{Ni}}_{57}{\mathrm{Mn}}_{18}{\mathrm{Ga}}_{21.45}{\mathrm{In}}_{3.55}$ alloy when simultaneously applying a moderate dual-external-field (uniaxial stress of 95 MPa and magnetic field of 2 T). Such a multicaloric $\mathrm{\ensuremath{\Delta}}{T}_{\mathrm{ad}}$ is 72% higher than the single elastocaloric cooling, which is ascribed to the larger transformation volume fractions obtained under dual fields. Additionally, benefiting from the reduction in critical stress by a bias magnetic field, ${\mathrm{Ni}}_{57}{\mathrm{Mn}}_{18}{\mathrm{Ga}}_{21.45}{\mathrm{In}}_{3.55}$ exhibits a good fatigue resistance with a relatively stable $\mathrm{\ensuremath{\Delta}}{T}_{\mathrm{ad}}$ of \ensuremath{-}5.7 K upon dual-field cycles of about 600 times. Our experimental results reveal that the multicaloric strategy based on the synergic magnetostructural transformation is feasible and promising for solid-state cooling under relatively lower driven fields.