Charge-order fluctuations and superconductivity in two-dimensional organic metals
Charge-order fluctuations and superconductivity in two-dimensional organic metals
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DOI：
10.1103/physrevb.89.174503
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发表时间：
2014-05-08
影响因子：
3.7
通讯作者：
Dressel, Martin
中科院分区：
文献类型：
--
作者：
Girlando, Alberto;Masino, Matteo;Dressel, Martin
我们报告了有机金属 β ''-(BEDT-TTF)(2)SF5CHFSO3 和超导体 β ''-(BEDT-TTF)(2)SF5CH2CF2SO3 中电荷级 (CO) 波动的全面拉曼和红外研究。通过扩展著名的 Kubo 模型来分析电荷敏感振动带，以获取两种状态之间平衡的光谱特征。在室温下，两种盐在两种不同电荷的分子状态之间表现出电荷波动，交换频率约为 6 x 10(11) s(-1)。金属盐的交换速率在低至10 K时保持大致恒定，而在超导体中，交换速率在200 K以下开始降低，并且在低至超导温度时出现“冻结”电荷有序态并与电荷序波动态共存。这些发现与其他光谱实验相矛盾，并提出了 β''BEDT-TTF 四分之一填充盐的暂定相图。
We report comprehensive Raman and infrared investigations of charge-order (CO) fluctuations in the organicmetal beta ''-(BEDT-TTF)(2)SF5CHFSO3 and superconductor beta ''-(BEDT-TTF)(2)SF5CH2CF2SO3. The chargesensitive vibrational bands are analyzed through an extension of the well-known Kubo model for the spectral signatures of an equilibrium between two states. At room temperature, both salts exhibit charge fluctuations between two differently charged molecular states with an exchange frequency of about 6 x 10(11) s(-1). The exchange rate of the metallic salt remains roughly constant down to 10 K, while in the superconductor, the exchange velocity starts to decrease below 200 K, and a "frozen" charge-ordered state emerges and coexists with the charge-order fluctuation state down to the superconducting temperature. These findings are confronted with other spectroscopic experiments, and a tentative phase diagram is proposed for the beta '' BEDT-TTF quarter-filled salts.