Refrigeration down to 0.16 K using a frustrated magnet Gd<sub>2</sub>B<sub>2</sub>MoO<sub>9</sub>.

Zhang, Yikun; Na, Yingzhe; Liu, Xinyang; Xiang, Junsen; Chen, Fengying; Li, Hai-Feng; Sun, Peijie; Zhou, Shengqiang et al. · Nat Commun · 2026

basic_science · Level V

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Abstract

Magnetic refrigeration, utilizing the magnetocaloric effect in solid-state magnets, has emerged as a promising cooling technology. The development of practical ultra-low-temperature magnetic refrigeration applications has been limited by the absence of high-performance magnetic refrigerants. Herein, we provide a frustrated Gadolinium-dominated magnet, Gd<sub>2</sub>B<sub>2</sub>MoO<sub>9</sub> oxide, which exhibits remarkable ultra-low temperature magnetocaloric performances. The maximum magnetic entropy changes reach 13.3 (76.6), 33.7 (194.0) and 45.1 (259.8) J/kgK (mJ/cm<sup>3</sup>K) under relatively low magnetic field changes of 0-1, 0-2 and 0-3 T, respectively. A minimum temperature of 0.16 K has been achieved by a custom-built quasi-adiabatic demagnetization apparatus. These magnetocaloric performances surpass those of the commercial ultra-low temperature magnetic refrigerant Gd<sub>3</sub>Ga<sub>5</sub>O<sub>12</sub> and outperform most of recently reported materials. Combined with its relatively high density and environmental stability, the geometrically frustrated Gd<sub>2</sub>B<sub>2</sub>MoO<sub>9</sub> oxide is established as an attractive ultra-low temperature magnetic refrigerant.