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Strong coupling effects in magnetocaloric materials are the key factor to achieve a large magnetic entropy change. Combining insights from experiments and ab initio calculations, we review relevant coupling phenomena, including atomic coupling, stress coupling, and magnetostatic coupling. For the investigations on atomic coupling, we have used Heusler compounds as a flexible model system. Stress coupling occurs in first‐order magnetocaloric materials, which exhibit a structural transformation or volume change together with the magnetic transition. Magnetostatic coupling has been experimentally demonstrated in magnetocaloric particles and fragment ensembles. Based on the achieved insights, we have demonstrated that the materials properties can be tailored to achieve optimized magnetocaloric performance for cooling applications.

A multi-stimuli cooling cycle can be used to increase the cyclic caloric performance of multicaloric materials like Ni–Mn–In Heusler alloys. However, the use of uniaxial compressive stress as an additional external stimulus to a magnetic field requires good mechanical stability. Improvement in mechanical stability and strength by doping has been shown in several studies. However, doping is always accompanied by grain refinement and a change in transition temperature. This raises the question of the extent to which mechanical strength is related to grain refinement, transition temperature, or precipitates. This study shows a direct comparison between a single-phase Ni–Mn–In and a two-phase Gd-doped Ni–Mn–In alloy with the same transition temperature and grain size. It is shown that the excellent magnetocaloric properties of the Ni–Mn–In matrix are maintained with doping. The isothermal entropy change and adiabatic temperature change are reduced by only 15% in the two-phase Ni–Mn–In Heusler alloy compared to the single-phase alloy, which results from a slight increase in thermal hysteresis and the width of the transition. Due to the same grain size and transition temperature, this effect can be directly related to the precipitates. The introduction of Gd precipitates leads to a 100% improvement in mechanical strength, which is significantly lower than the improvement observed for Ni–Mn–In alloys with grain refinement and Gd precipitates. This reveals that a significant contribution to the improved mechanical stability in Gd-doped Heusler alloys is related to grain refinement.

In this study, a combination of induction melting and suction casting methods were used to produce a series of high-purity samples of L a 1 − x R x F e 11.6 S i 1.4 system with R = Pr and Nd for x = 0.1, 0.2, 0.3 and 0.4. The Curie temperature ( T C ) is lowered for all the substituted compositions compared to L a F e 11.6 S i 1.4 , while the hysteresis area shows a small increase for higher amounts of substitution element. The estimated isothermal magnetic entropy change ( Δ S T ) of all samples are in the same range with a maximum of 25  J k g − 1 K − 1 . The Δ T a d , under the cyclic conditions for all compositions decreases compared to the first application of the magnetic field due to the thermal hysteresis. Applying the Bean–Rodbell model to the isothermal magnetization data, the temperature dependence of the critical field was found. Excluding the phase transition region, the model accurately describes the temperature and field dependence of magnetization above and below the magnetic transition, highlighting the magnetic moment change of the system due to the structural transformation.

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