Title: Gd(OH)F2: A Promising Cryogenic Magnetic Refrigerant

Authors: Qiaofei Xu, Boliang Liu, Mingyu Ye, Guilin Zhuang*, Lasheng Long*, and Lansun Zheng

Abstract: Magnetic refrigerants with a large magnetocaloric effect (MCE) in a wide temperature range and low magnetic ordering temperature (T_o) in the sub-kelvin temperature region are not only crucial for adiabatic demagnetization refrigeration but also open up a broader parameter space for the optimal design of adiabatic demagnetization refrigerators. However, such magnetic refrigerants are extremely rare because they require magnetic materials to simultaneously satisfy three conditions: low T_o, weak magnetic interaction, and high magnetic density. Here, we report the syntheses, heat capacities, and magnetic properties of Gd(OH)_3–xF_x (1: x = 1, 2: x ≈ 1.5, and 3: x = 2), demonstrating for the first time that the introduction of fluoride anions into antiferromagnetic Gd(OH)₃ can effectively regulate its T_o. Significantly, 3 not only has a T_o of 0.5 K but also exhibits a large MCE in the temperature range from 0.5 to 4 K, representing the best magnetic refrigerant reported to date in the temperature range of 0.5–4 K from the viewpoint of the MCE.

Full-Link: https://pubs.acs.org/doi/10.1021/jacs.2c04840