Ultralow-field magnetocaloric materials for compact magnetic refrigeration
Peng Liu, Dongsheng Yuan, Chao Dong, Gaoting Lin, Encarnación G. Vı́llora, Ji Qi, Xinguo Zhao, Kiyoshi Shimamura, Jie Ma, Junfeng Wang, Zhidong Zhang, Bing Li
Abstract
Abstract 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 LiREF 4 (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 LiHoF 4 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.