Achieving Magnetic Refrigerants with Large Magnetic Entropy Changes and Low Magnetic Ordering Temperatures

Abstract

Adiabatic demagnetization refrigeration (ADR) is a promising cooling technology with high efficiency and exceptional stability in achieving ultralow temperatures, playing an indispensable role at the forefront of fundamental and applied science. However, a significant challenge for ADR is that existing magnetic refrigerants struggle to concurrently achieve low magnetic ordering temperatures (T 0 ) and substantial magnetic entropy changes (−ΔS m ) at ultralow temperatures. In this work, we propose the combination of Gd 3+ and Yb 3+ to effectively regulate both −ΔS m and T 0 in ultralow temperatures. Notably, the −ΔS m values for Gd 0.1 Yb 0.9 F 3 (1) and Gd 0.3 Yb 0.7 F 3 (2) in the 0.4−1.0 K range exceed those of all previously reported magnetic refrigerants within this temperature interval, positioning them as the most efficient magnetic refrigerants for the third stage to date. Although the −ΔS m values for Gd 0.5 Yb 0.5 F 3 (3) in 1−4 K are less than those of the leading magnetic refrigerant Gd(OH)F 2 , the −ΔS m values for Gd 0.7 Yb 0.3 F 3 (4) in 1−4 K at 2 T surpass those of all magnetic refrigerants previously documented within the same temperature range, making it the superior magnetic refrigerant for the fourth stage identified thus far.