Thermodynamics of the Kitaev honeycomb magnet $\alpha \text{−}\mathrm{Ru}{\mathrm{Cl}}_3$ is studied for different directions of in-plane magnetic field using measurements of the magnetic Grüneisen parameter ${\mathrm{\Gamma }}_B$ and specific heat $C$. We identify two critical fields $B_c^{\mathrm{AF}1}$ and $B_c^{\mathrm{AF}2}$ corresponding, respectively, to a transition between two magnetically ordered states and the loss of magnetic order toward a quantum paramagnetic state. The $B_c^{\mathrm{AF}2}$ phase boundary reveals a narrow region of magnetic fields where inverse melting of the ordered phase may occur. No additional transitions are detected above $B_c^{\mathrm{AF}2}$ for any direction of the in-plane field, although a shoulder anomaly in ${\mathrm{\Gamma }}_B$ is observed systematically at $8–10\mathrm{T}$ . Large field-induced entropy effects imply additional low-energy excitations at low fields and/or strongly field-dependent phonon entropies. Our results establish universal features of $\alpha \text{−}\mathrm{Ru}{\mathrm{Cl}}_3$ in high magnetic fields and challenge the presence of a field-induced Kitaev spin liquid in this material.

中文翻译：

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α-RuCl3随角度变化的热力学

Kitaev蜂窝磁铁的热力学 $\alpha \text{-}茹{氯}_3$ 通过测量磁性Grüneisen参数来研究平面内磁场的不同方向 ${\mathrm{\Gamma }}_{乙}$ 和比热 $C$。我们确定了两个关键领域${乙}_C^{\mathrm{自动对焦}\mathrm{1个}}$ 和 ${乙}_C^{\mathrm{自动对焦}\mathrm{2个}}$分别对应于两个磁性有序状态之间的过渡以及朝向量子顺磁态的磁性无序。这${乙}_C^{\mathrm{自动对焦}\mathrm{2个}}$相边界揭示了磁场的狭窄区域，在该区域中可能发生有序相的反向熔化。上方未检测到其他过渡${乙}_C^{\mathrm{自动对焦}\mathrm{2个}}$ 平面内视场的任何方向，尽管肩部异常 ${\mathrm{\Gamma }}_{乙}$ 被系统地观察到 $8–10\mathrm{Ť}$。大场感应的熵效应意味着在低场和/或与场相关的声子熵很强的情况下会产生额外的低能激发。我们的结果确定了$\alpha \text{-}茹{氯}_3$ 在强磁场中，并挑战这种材料中场感应的Kitaev自旋液体的存在。