Dephasing dynamics of photoexcited state in correlated electron system

相关电子系统中光激发态的相移动力学

• 批准号: 16340085
• 负责人: IWAI Shinichiro
• 金额: $ 10.43万
• 依托单位: Tohoku University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2004
• 资助国家: 日本
• 起止时间: 2004 至 2006
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-16340085/
• 关键词: Correlated electron system; Photoinduced phase transition; Polarization dephasing; Mott insulator; Charge order; 超高速分光; 縮退4光波混合

Photo-response of correlated electron (CE) system has attracted much attention because of their ultrafast dynamics aspects. In this research project, I) We have investigated dephasing dynamics of photoexcited state in one-dimesional Mott insulator [Ni(chxn)_2Br]Br_2 by using 2-pulse degenerative four-wave mixing (DFWM), II) ultrafast photoinduced insulator-to metal transition (PIMT) was detected in two-dimensional organic conductor (BEDT-TTF)_2X by mid-IR femtosecond pump-probe spectroscopy for the first time.I)In the DFWM study of [Ni(chxn)_2Br]Br_2, i) for strong excitation condition, the slower decay component (6 ps) of DFWM signal appears, while only sub-ps component is observable for the weak excitation. ii) A temperature dependence of the slow decay for the strong excitation can not be understood in terms of the holon-doublon (h-d) cluster-optical phonon interaction. The temperature dependence of the dynamics can be summarized as follows; a) sub-ps component, which is detected fo … More r T>30 K and becomes shorter for T<100 K, b) several ps component which becomes shorter for T >100 K. The relaxation process of b) can be explained by using the interaction between the carrier and the optical phonon. Nevertheless, the a) is suggested to be related to the magnon excitation since the temperature dependence of the decay constants and their fractions resemble the temperature dependence of the magnetic susceptibility. Moreover, for b), although, the frequency of the interacting optical phonon is evaluated to be same as that of for weak excitation limit, coupling constant is smaller for one order of magnitude. These results indicate that 1) h-d cluster, which is generated by the strong excitation, is scattered by phonon and magnon, 2) the coupling constant between the h-d cluster and optical phonon is markedly suppressed, 3) resultantly, decay reflecting the magnon scattering is considered to appear.II)In the research of the two-dimensional organic conductor (BEDT-TTF)_2X, ultrafast and efficient (>100 molecules /photon) photoinduced insulator-to metal transition was observed. The critical slowing down of the photoinduced metallic state and the coherent phonon reflecting the inhomogeneous structure of the photoinduced domain.Our results will provide the useful information for designing the material for ultarfast CE switching devise whose mechanisms are third order optical nonlinearity or photoinduced phase transition, respectively. Less

关联电子(CE)体系的光响应因其超快的动力学特性而备受关注。在本研究项目中，我们首次利用双脉冲简并四波混频(DFWM)研究了一维Mott绝缘体[Ni(Chxn)_2br]Br2中光激发态的退相动力学，ii)利用中红外飞秒泵浦探测光谱首次探测到了二维有机导体(BEDT-TTF)_2X中超快光致绝缘体-金属跃迁(PIMT)。I.)在强激发条件下，DFWM信号的较慢分量(PS)出现衰减而对于弱激发，只能观察到亚pS分量。Ii)强激发的慢衰变与温度的关系不能用Holon-Doublon(h-d)团簇-光学声子相互作用来解释。动力学的温度依赖性可概括如下：a)在…中检测到的亚PS分量T&t；30K越大，T&lt；100K越短；b)几个ps分量随T&gt；100K而变短。b)的驰豫过程可以用载流子与光学声子之间的相互作用来解释。然而，a)被认为与磁振子激发有关，因为衰变常数及其分数的温度依赖关系类似于磁化率的温度依赖关系。此外，对于b)，尽管相互作用光学声子的频率被估计为与弱激发极限的频率相同，但耦合常数对于一个数量级来说要小一个数量级。这些结果表明：1)强激发产生的h-d团簇被声子和磁振子散射，2)h-d团簇与光学声子之间的耦合常数被显著抑制，3)出现了反映磁振子散射的衰变。ii)在二维有机导体(BEDT-TTF)_2X的研究中，观察到了超快而高效的(&gt；100个分子/光子)诱导的绝缘体到金属的光致转变。光致金属态和相干声子的临界慢化反映了光致磁畴的不均匀结构。我们的结果将为分别以三阶光学非线性和光致相变为机制的超快速CE开关器件的材料设计提供有用的信息。较少

项目成果

光媒体および光素子

光学介质和光学元件

• 发表时间: 2005

Photoinduced melting of a stripe-type charge-order and metallic domain formation in a layered BEDT-TTF-based organic salt

• DOI: 10.1103/physrevlett.98.097402
• 发表时间: 2007-03-02
• 期刊: PHYSICAL REVIEW LETTERS
• 影响因子: 8.6
• 作者: Iwai, S.;Yamamoto, K.;Nishio, Y.
• 通讯作者: Nishio, Y.

Ultrafast Phase Control in One-Dimensional Correlated Electron Systems

一维相关电子系统中的超快相位控制

• 发表时间: 2006
• 期刊: Journal of the Physical Society of Japan 75
• 作者: S.Iwai;H.Okamoto
• 通讯作者: H.Okamoto

Coherent control of charge and lattice dynamics in a photoinduced neutral-to-ionic transition of charge-transfer compound

电荷转移化合物光诱导中性到离子转变中电荷和晶格动力学的相干控制

• 发表时间: 2006
• 期刊: Phys. Rev. Lett. 96
• 作者: M.Fujiwara;A.I.Titov;T.Kawabata et al.;M.Uchida et al.;S.Nakayama et al.;S.Iwai;S.Iwai;S.Iwai
• 通讯作者: S.Iwai

光媒体およびそれを用いた光素子

光学介质和使用该光学介质的光学装置

• 发表时间: 2005