Lattice Effects and Entropy Release at the Low-Temperature Phase Transition in the Spin-Liquid Candidate κ-(BEDT-TTF)2Cu2(CN)3
Lattice Effects and Entropy Release at the Low-Temperature Phase Transition in the Spin-Liquid Candidate κ-(BEDT-TTF)2Cu2(CN)3
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DOI：
10.1103/physrevlett.104.016403
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发表时间：
2010-01-08
影响因子：
8.6
通讯作者：
Lang, M.
中科院分区：
文献类型：
--
作者：
Manna, R. S.;de Souza, M.;Lang, M.
通过测量单轴膨胀系数α(i)、比热和磁化率，研究了自旋液体候选kappa-(BEDT-TTF)(2)Cu-2(CN)(3)。特别强调了 6 K 附近的神秘异常——一种潜在的自旋液体不稳定性。在 6 K 时观察到了明显且强烈的各向异性晶格效应，清楚地将该特征识别为二阶相变。由于 alpha(i) 存在较大异常，格鲁内森标度的应用使我们能够确定相应的比热贡献和熵释放。后者与现有自旋模型的比较表明，仅自旋自由度不能解释相变。讨论了涉及电荷自由度的场景。
The spin-liquid candidate kappa-(BEDT-TTF)(2)Cu-2(CN)(3) has been studied by measuring the uniaxial expansion coefficients alpha(i), the specific heat, and magnetic susceptibility. Special emphasis was placed on the mysterious anomaly around 6 K-a potential spin-liquid instability. Distinct and strongly anisotropic lattice effects have been observed at 6 K, clearly identifying this feature as a second-order phase transition. Owing to the large anomalies in alpha(i), the application of Gruneisen scaling has enabled us to determine the corresponding specific heat contribution and the entropy release. Comparison of the latter with available spin models suggests that spin degrees of freedom alone cannot account for the phase transition. Scenarios involving charge degrees of freedom are discussed.