Exceptional Cooling Capacity of LiGd0.1Yb0.9F4 at Sub‐Kelvin Temperatures

• DOI: 10.1002/adma.202414226
• Publication Date: 2025-02-06T06:40:41Z
• Authors: Qiao‐Fei Xu; Peng Zhao; Man‐Ting Chen; Ruo‐Tong Wu; Wei Dai; La‐Sheng Long; Lan‐Sun Zheng

Adiabatic demagnetization refrigeration, which utilizes the magnetocaloric effect of magnetic refrigerants, stands as sole cooling technology capable achieving sub-Kelvin temperatures efficiently and reliably without relying on scarce 3He resources or gravity. However, current refrigerants encounter challenges such structural instability in vacuum under mild heating, along with small entropy change (-ΔSm) values, significantly limit their practical applications. Here a water-free refrigerant, LiGd0.1Yb0.9F4 is reported, prepared by introducing Li⁺ ions to reduce dipolar interactions between Gd3+ and/or Yb3+ ions. Notably, this refrigerant possesses ordering temperature 85 mK, while its experimental -ΔSm reaches up 136 mJ cm-3 K-1 (0.68 K 2 T), more than three times theoretical value CrK(SO4)2·12H2O. Significantly, not only cools test sample low 160 mK but also achieves specific capacity 46.943 T-1 at 300 mK. Remarkably, double that commercial CrK(SO4)2·12H2O, representing one most notable values reported among all known operating temperatures.