Ising Supercriticality and Universal Magnetocalorics in Spiral Antiferromagnet Nd$_3$BWO$_9$
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| Format: | Preprint |
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2026
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| _version_ | 1866915928880447488 |
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| author | Liu, Xinyang Lv, Enze Cui, Xueling Ge, Han Song, Fangyuan Tian, Zhaoming Su, Gang Zhao, Kan Xiang, Junsen Sun, Peijie Li, Wei |
| author_facet | Liu, Xinyang Lv, Enze Cui, Xueling Ge, Han Song, Fangyuan Tian, Zhaoming Su, Gang Zhao, Kan Xiang, Junsen Sun, Peijie Li, Wei |
| contents | The celebrated analogy between the pressure-temperature phase diagram of a liquid-gas system and the field-temperature phase diagram of 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 $μ_0H_{\mathrm{c}} \simeq 1.04$ T and $T_{\mathrm{c}} \simeq 0.3$ K. Above the CEP, an Ising supercritical regime} emerges with supercritical crossover lines that adhere to a universal scaling law, as evidenced by the specific heat, magnetic susceptibility, and magnetocaloric measurements. Remarkably, we observe a highly sensitive field dependence in the magnetic cooling near the emergent CEP, characterized by a divergent magnetic Grüneisen ratio $Γ_H \propto 1/t^{β+γ-1}$, with $β+ γ\simeq 1.563$ the critical exponents of 3D Ising universality class and $t \equiv (T-T_{\rm c})/T_{\rm c}$ the reduced temperature. Our adiabatic demagnetization measurements on Nd$_3$BWO$_9$ reveal a lowest temperature of 195~mK, achieved from the initial condition of 2 K and 4 T. Our findings open a new avenue for studying supercritical phenomena and magnetic cooling in rare-earth RE$_3$BWO$_9$ family and, more broadly, in Ising-anisotropic magnets such as spin ices. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2601_07810 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Ising Supercriticality and Universal Magnetocalorics in Spiral Antiferromagnet Nd$_3$BWO$_9$ Liu, Xinyang Lv, Enze Cui, Xueling Ge, Han Song, Fangyuan Tian, Zhaoming Su, Gang Zhao, Kan Xiang, Junsen Sun, Peijie Li, Wei Strongly Correlated Electrons Materials Science The celebrated analogy between the pressure-temperature phase diagram of a liquid-gas system and the field-temperature phase diagram of 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 $μ_0H_{\mathrm{c}} \simeq 1.04$ T and $T_{\mathrm{c}} \simeq 0.3$ K. Above the CEP, an Ising supercritical regime} emerges with supercritical crossover lines that adhere to a universal scaling law, as evidenced by the specific heat, magnetic susceptibility, and magnetocaloric measurements. Remarkably, we observe a highly sensitive field dependence in the magnetic cooling near the emergent CEP, characterized by a divergent magnetic Grüneisen ratio $Γ_H \propto 1/t^{β+γ-1}$, with $β+ γ\simeq 1.563$ the critical exponents of 3D Ising universality class and $t \equiv (T-T_{\rm c})/T_{\rm c}$ the reduced temperature. Our adiabatic demagnetization measurements on Nd$_3$BWO$_9$ reveal a lowest temperature of 195~mK, achieved from the initial condition of 2 K and 4 T. Our findings open a new avenue for studying supercritical phenomena and magnetic cooling in rare-earth RE$_3$BWO$_9$ family and, more broadly, in Ising-anisotropic magnets such as spin ices. |
| title | Ising Supercriticality and Universal Magnetocalorics in Spiral Antiferromagnet Nd$_3$BWO$_9$ |
| topic | Strongly Correlated Electrons Materials Science |
| url | https://arxiv.org/abs/2601.07810 |