Authors
Xinyang Liu, Enze Lv, Xueling Cui, Han Ge, Fangyuan Song, Zhaoming Tian, Gang Su, Kan Zhao, Junsen Xiang, Peijie Sun, Wei Li
Published in
Physical review letters. Volume 136. Issue 24. Pages 246502. Jun 19, 2026.
Abstract
The celebrated analogy between the pressure-temperature phase diagram of a liquid-gas system and the field-temperature phase diagram of a ferromagnet has long been a cornerstone for understanding universality of phase transitions and critical phenomena. Here we extend this analogy to a highly frustrated antiferromagnet, the spiral Ising compound Nd_{3}BWO_{9} with kagome layers. In its phase diagram, we identify a metamagnetic transition line with a critical endpoint (CEP) located at μ_{0}H_{c}≃1.04 T and T_{c}≃0.3 K. Above the CEP, an Ising supercritical regime emerges with crossover lines that follow a universal scaling law, as evidenced by the specific heat, magnetic susceptibility, and magnetocaloric measurements. Remarkably, we observe critically enhanced magnetic cooling near the emergent CEP, characterized by a divergent magnetic Grüneisen ratio Γ_{H}∝1/t^{β+γ-1}, with β+γ≃1.563 the sum of critical exponents of the 3D Ising universality class and t≡(T-T_{c})/T_{c} the reduced temperature. Adiabatic demagnetization from 2 K and 4 T reaches a minimum temperature of 195 mK, via a self-cascading process that combines supercritical and topological cooling. Our findings open a new avenue for studying supercritical phenomena and magnetic refrigeration with the frustrated rare-earth compounds RE_{3}BWO_{9} and, more broadly, in Ising-anisotropic antiferromagnets such as spin ices.
PMID:
42412442
Bibliographic data and abstract were imported from PubMed on 07 Jul 2026.
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