Abstract
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 which \(\sim \) 50 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 below \(\sim \) 18 K, suggesting a fluctuating superconductivity in the conducting domains. Furthermore, the component persists up to at least \(\sim \) 50 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 alloy κ-(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.
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We thank Edanz Group (www.edanzediting.com/ac) for editing a draft of this manuscript.
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This work was supported by JSPS KAKENHI Grant Numbers 15K17685, 18J10148, and 19H05826.
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Nakagawa, K., Tsuchiya, S., Taniguchi, H. et al. Polarized Time-Resolved Spectroscopy of Electronic Phase Separation in a Dimer-Mott Organic Insulator. J Supercond Nov Magn 33, 2427–2433 (2020). https://doi.org/10.1007/s10948-019-05385-1
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DOI: https://doi.org/10.1007/s10948-019-05385-1