Polarized Time-Resolved Spectroscopy of Electronic Phase Separation in a Dimer-Mott Organic Insulator
Polarized Time-Resolved Spectroscopy of Electronic Phase Separation in a Dimer-Mott Organic Insulator
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二聚体莫特有机绝缘体中电子相分离的偏振时间分辨光谱
DOI：
10.1007/s10948-019-05385-1
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发表时间：
2020
影响因子：
1.8
通讯作者：
Hiromi Taniguchi & Yasunori Toda
中科院分区：
文献类型：
--
作者：
Koichi Nakagawa;Satoshi Tsuchiya;Hiromi Taniguchi & Yasunori Toda
有机单晶$\kappa -\left [ \left]的电子态（\text {d-BEDT-TTF} \right）_{0.5} \left（\text {h-BEDT-TTF}\right）_{0.5}\right ]_{2}$ Cu[N（CN）2]Br，其中50%的BEDT-TTF分子被全氘代分子取代（d-BEDT-TTF），其特征在于电阻和极化时间分辨光谱测量。我们发现，虽然电阻没有超导转变的迹象，极化时间分辨光谱揭示了一个缓慢的衰减动力学与超导相在低温下。结果表明，在一阶Mott转变附近的绝缘相和超导相之间的相分离。此外，我们发现，这个缓慢的组件显示出一个陡峭的增加低于18 K，这表明在导电域的超导波动。此外，该分量至少持续到50 K，这与之前能斯特效应测量观察到的异常磁场相关信号的起始温度几乎一致（Nam等人，Sci. Rep.3：3390，2013）的合金κ-（BEDT-TTF）2Cu[N（CN）2] Cl 0.27Br 0.73。虽然对这些异常的解释仍有争议，但存在着在非常高的温度下发生超导配对的可能性。
The electronic state of the organic single crystal $\kappa -\left [ \left (\text {d-BEDT-TTF} \right )_{0.5} \left (\text {h-BEDT-TTF}\right )_{0.5}\right ]_{2}$ Cu[N(CN)2]Br, in which50 percent of the BEDT-TTF molecules are substituted by fully deuterated molecules (d-BEDT-TTF), has been characterized by resistance and polarized time-resolved spectroscopy measurements. We found that while the resistance shows no sign of a superconducting transition, the polarized time-resolved spectroscopy reveals a slow decay dynamics associated with the superconducting phase at a low temperature. The result suggests phase separation between the insulating and superconducting phases in the vicinity of the first-order Mott transition. In addition, we found that this slow component shows a steep increase below18 K, suggesting a fluctuating superconductivity in the conducting domains. Furthermore, the component persists up to at least50 K, which is almost consistent with the onset temperature of the anomalous magnetic-field-dependent signals observed by the previous Nernst effect measurements (Nam et al. Sci. Rep.3:3390, 2013) of the alloyκ-(BEDT-TTF)2Cu[N(CN)2]Cl0.27Br0.73. While interpretation of these anomalies is still debatable, there exists a possibility of the onset of superconducting paring at a very high temperature.