Ultralow-field magnetocaloric materials for compact magnetic refrigeration

Magnetic refrigeration around the liquid-helium temperature is crucial for various technological applications. While gallium gadolinium garnet (GGG) is a benchmark material, its limited magnetic entropy change, reliance on superconducting magnets, and large device size hinder its use. This study demonstrates that LiREF₄ (RE = rare earth) single crystals exhibit superior magnetocaloric performance compared to GGG. LiHoF₄ achieves a record-high magnetic entropy change of 16.7 Jkg⁻¹K⁻¹ under a 5 kOe field, significantly exceeding GGG's 1.0 Jkg⁻¹K⁻¹. The combination of low driving fields, large entropy changes, and excellent thermal/magnetic reversibility makes LiREF₄ ideal for compact magnetic refrigeration near liquid-helium temperatures.

Peng Liu, Dongsheng Yuan, Chao Dong, Gaoting Lin, Encarnación G. Villora, Ji Qi, Xinguo Zhao, Kiyoshi Shimamura, Jie Ma, Junfeng Wang, Zhidong Zhang, Bing Li