Magnetic refrigeration around the liquid-helium temperature plays a critical role in many technological sectors. Even if gallium gadolinium garnet (GGG) has been regarded as the benchmark, its application is highly limited by the small magnetic entropy changes, the requirement of superconducting magnets, and the large device sizes. Here, we report that LiREF₄ (RE = rare earth) single crystals exhibit significantly superior magnetocaloric performance levels to commercial GGG. Under a small magnetic field of 5 kOe, which can be easily achieved by a permanent magnet, the magnetic entropy change reaches a record-high value of 16.7 J kg⁻¹ K⁻¹ in LiHoF₄ in contrast to the value of 1.0 J kg⁻¹ K⁻¹ in GGG. The combination of small driving fields, large entropy changes, and excellent thermal and/or magnetic reversibility enables this series to be employed as the ideal working material for compact magnetic refrigeration around the liquid-helium temperature.

液氦温度附近的磁制冷在许多技术领域发挥着关键作用。即使镓钆石榴石（GGG）被视为基准，但由于其磁熵变小、超导磁体的要求以及器件尺寸大，其应用受到很大限制。在这里，我们报告 LiREF ₄（RE = 稀土）单晶表现出明显优于商业 GGG 的磁热性能水平。在永磁体可以轻松实现的 5 kOe 小磁场下， LiHoF ₄的磁熵变达到创纪录的 16.7 J kg -1 K -1 值，而相比之下，磁熵^变为 1.0 ^J kg ^-1  K ^-1在GGG。小驱动场、大熵变以及出色的热和/或磁可逆性的结合使该系列成为液氦温度附近紧凑型磁制冷的理想工作材料。