标题： 应变能增强的二级磁相变材料中的室温磁热效应 显示英文标题

标题： Strain energy enhanced room-temperature magnetocaloric effect in second-order magnetic transition materials

摘要： 大磁熵变（deltaSM）可以在磁场下实现显著的热转换，并直接增强磁制冷效应的效率，这为提高制冷能力和效率提供了一种开创性的环保固态策略。 第二类磁相变（SOMT）材料相比大多数第一类磁相变材料具有更宽的deltaSM峰且没有热滞回，这使其在磁制冷中非常有吸引力，尤其是在室温范围内。 在这里，我们报告了单晶Mn5Ge3在室温下的deltaSM显著增强。 在这个SOMT体系中，我们在T = 300K时将-deltaSM从3.5 J/kgK提高了60%，达到5.6 J/kgK。 这种deltaSM的显著增强是通过高压约束变形有意引入应变能实现的。 实验结果和蒙特卡罗模拟都表明，deltaSM的增强来源于变形后由应变能引起的微观应变和晶格变形。 这种应变能将重构该铁磁系统的能量景观并增强磁化强度，从而产生巨大的磁制冷响应强度。 我们的研究提供了一种增加磁熵变的方法，可能为探索先进的磁制冷材料提供新的思路。 显示英文摘要

摘要： Large magnetic entropy change (deltaSM) can realize a prominent heat transformation under the magnetic field and directly strengthen the efficacy of the magnetocaloric effect, which provides a pioneering environmentally friendly solid-state strategy to improve refrigeration capacities and efficiencies. The second-order magnetic transition (SOMT) materials have broader deltaSM peaks without thermal hysteresis compared with most first-order magnetic transition materials, making them highly attractive in magnetic refrigeration, especially in the room temperature range. Here, we report a significant enhancement of deltaSM at room temperature in single-crystal Mn5Ge3. In this SOMT system, we realize a 60% improvement of -deltaSM from 3.5 J/kgK to 5.6 J/kgK at T = 300K. This considerable enhancement of deltaSM is achieved by intentionally introducing strain energy through high-pressure constrained deformation. Both experimental results and Monte Carlo simulations demonstrate that the enhancement of deltaSM originates from the microscopic strain and lattice deformation induced by strain energy after deformation. This strain energy will reconstruct the energy landscape of this ferromagnetic system and enhance magnetization, resulting in a giant intensity of magnetocaloric responses. Our findings provide an approach to increase magnetic entropy change and may give fresh ideas for exploring advanced magnetocaloric materials.