We investigate the quench and real-time formation of the Mott state and photoexcited carrier relaxation dynamics in the Mott insulator $\kappa \text{−}{\left(\mathrm{B}\mathrm{E}\mathrm{D}\mathrm{T}\text{−}\mathrm{T}\mathrm{T}\mathrm{F}\right)}_2\mathrm{Cu}\left[\mathrm{N}{\left(\mathrm{C}\mathrm{N}\right)}_2\right]\mathrm{Cl}\left(\kappa \text{−}\mathrm{Cl}\right)$ and the superconductor $\kappa \text{−}{\left(\mathrm{B}\mathrm{E}\mathrm{D}\mathrm{T}\text{−}\mathrm{T}\mathrm{T}\mathrm{F}\right)}_2\mathrm{Cu}\left[\mathrm{N}{\left(\mathrm{C}\mathrm{N}\right)}_2\right]\mathrm{Br}\left(\kappa \text{−}\mathrm{Br}\right)$ using three-pulse femtosecond optical spectroscopy, where BEDT-TTF is bis(ethylenedithio)tetrathiafulvalene. In both salts, we find that transient reflectivity amplitude gradually recovers with time after strong near-infrared pulse quench, but its relaxation time is nearly constant throughout. This indicates that in $\kappa$-Cl, the energy gap for charge excitations is filled rather than closed by photoinduced carriers of only $\sim 0.5$% per dimer. The Mott state is re-formed on a few-picosecond timescale with the disappearance of the in-gap photodoping-induced states near the Fermi energy. In $\kappa$-Br, a behavior similar to that in $\kappa$-Cl is observed and attributed to the disorder-induced phase-separated Mott insulating regions.

中文翻译：

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三脉冲泵浦探针光谱观察到的强相关 BEDT-TTF 分子导体中莫特态猝灭和形成的超快动力学

我们研究了莫特绝缘体中莫特态的猝灭和实时形成以及光激发载流子弛豫动力学 $\kappa \text{-}{\left(\mathrm{乙}\mathrm{乙}\mathrm{D}\mathrm{吨}\text{-}\mathrm{吨}\mathrm{吨}\mathrm{F}\right)}_2铜\left[\mathrm{N}{\left(\mathrm{C}\mathrm{N}\right)}_2\right]氯\left(\kappa \text{-}氯\right)$ 和超导体 $\kappa \text{-}{\left(\mathrm{乙}\mathrm{乙}\mathrm{D}\mathrm{吨}\text{-}\mathrm{吨}\mathrm{吨}\mathrm{F}\right)}_2铜\left[\mathrm{N}{\left(\mathrm{C}\mathrm{N}\right)}_2\right]溴\left(\kappa \text{-}溴\right)$使用三脉冲飞秒光谱，其中 BEDT-TTF 是双（亚乙基二硫）四硫富瓦烯。在这两种盐中，我们发现瞬态反射幅度在强近红外脉冲猝灭后随时间逐渐恢复，但其弛豫时间始终几乎恒定。这表明在$\kappa$-Cl，电荷激发的能隙被填充而不是被光生载流子封闭$～0.5$每个二聚体的百分比。随着费米能量附近的带隙内光掺杂诱导态的消失，莫特态在几皮秒的时间尺度上重新形成。在$\kappa$-Br，行为类似于 $\kappa$-Cl 被观察到并归因于无序诱导的相分离莫特绝缘区域。