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 ($\mathrm{\Delta }{T}_{\mathrm{ad}}$) 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 $\mathrm{\Delta }{T}_{\mathrm{ad}}$ of −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 $\mathrm{\Delta }{T}_{\mathrm{ad}}$ 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 $\mathrm{\Delta }{T}_{\mathrm{ad}}$ of −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.

Multicaloric effect refers to a thermal response of materials driven by multiple external fields. In this work, we explore the possibility by adopting multicaloric strategy to improve the transformation reversibility and manipulate the optimal operating temperature window in (Ni43Mn47Sn10)99.5Tb0.5 using a bespoke multicaloric effect characterization system. It is found that the reversibility of stress induced transformation could be significantly improved with the application of an extra magnetic field. More importantly, the operating temperature window of elastocaloric effect is shifted by ∼4 K to the lower temperature by applying a magnetic field of 4 T. Our experimental results reveal that such a dual-field multicaloric strategy is feasible and promising for improving the transformation reversibility and tuning the optimal operating temperature window for alloys with a magnetostructural transformation.

The significant negative thermal expansion (NTE) that occurs in La(Fe,Si)₁₃-based alloys during magnetic transition make them promising to combine with positive thermal expansion (PTE) materials to obtain near-zero thermal expansion (NZTE) materials. However, La(Fe,Si)₁₃-based alloys with NTE generally show intrinsic poor mechanical properties. Here, thermal expansion properties are optimized by adding Ag in La_0.6Ce_0.4(Fe_0.91Co_0.09)_11.9Si_1.1 to form a multi-phase structure exhibiting enhanced compressive strength. Through spark plasma sintering (SPS) and annealing, the samples consisted of α-Fe(Co,Si), NaZn₁₃-type, and LaAg₂ phases. When the annealing temperature reaches 1323 K, LaAg₂ disappears and is replaced by La₂O₃. The LaAg₂ phase and α-Fe(Co,Si) phase contribute as PTE materials to compensate for the NTE of the NaZn₁₃-type phase. Near-zero thermal expansion was achieved in the temperature range of 240–294 K, with a coefficient of thermal expansion (CTE) of 3.5 ppm/K at a 9.581 at.% Ag content. Benefiting from the uniform phase distribution and coordinated deformation, the samples obtained high mechanical strengths, with fracture stresses of 1481.1 MPa for the 15 wt.% Ag sample. This work provides a promising route for high-strength and near-zero thermal expansion Ag/La(Fe,Si)₁₃ composites.