The giant magnetocaloric effect, in which large thermal changes are induced in a material on the application of a magnetic field, can be used for refrigeration applications, such as the cooling of systems from a small to a relatively large scale. However, commercial uptake is limited. We propose an approach to magnetic cooling that rejects the conventional idea that the hysteresis inherent in magnetostructural phase-change materials must be minimized to maximize the reversible magnetocaloric effect. Instead, we introduce a second stimulus, uniaxial stress, so that we can exploit the hysteresis. This allows us to lock-in the ferromagnetic phase as the magnetizing field is removed, which drastically removes the volume of the magnetic field source and so reduces the amount of expensive Nd–Fe–B permanent magnets needed for a magnetic refrigerator. In addition, the mass ratio between the magnetocaloric material and the permanent magnet can be increased, which allows scaling of the cooling power of a device simply by increasing the refrigerant body. The technical feasibility of this hysteresis-positive approach is demonstrated using Ni–Mn–In Heusler alloys. Our study could lead to an enhanced usage of the giant magnetocaloric effect in commercial applications.

巨大的磁热效应，其中在施加磁场时会在材料中引起较大的热变化，可用于制冷应用，例如将系统从小规模冷却到较大规模。但是，商业吸收是有限的。我们提出了一种磁冷却的方法，该方法摒弃了必须将磁结构相变材料固有的磁滞最小化以最大化可逆磁热效应的传统思想。相反，我们引入了第二种刺激，即单轴应力，以便我们可以利用磁滞现象。这使我们能够在消除磁化场时锁定铁磁相，从而极大地消除了磁场源的体积，从而减少了磁性冰箱所需的昂贵的Nd-Fe-B永磁体的数量。另外，可以增加磁热材料和永磁体之间的质量比，这允许简单地通过增加制冷剂主体来缩放装置的冷却能力。Ni-Mn-In Heusler合金证明了这种磁滞正方法的技术可行性。我们的研究可能会导致在商业应用中更多地利用巨大的磁热效应。