Photoinduced Vibronic Soft mode Dynamics in Ferroelectric Quantum Cooperative Phenomena

铁电量子合作现象中的光致电子振动软模动力学

• 批准号: 17340088
• 负责人: TAKESADA Masaki
• 金额: $ 9.29万
• 依托单位: Hokkaido University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2005
• 资助国家: 日本
• 起止时间: 2005 至 2007
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-17340088/
• 关键词: photo induced phase transition; quantum paraelectrics; inorganic ferroelectrics; vibronic soft mode; soft mode dynamics; bismuth lavered perovskite; photoinduced quantum cooperative phenomenon; photoinduced dielectric susceptibility; ダイナミクス; 低振動数

Phase transition and its control by external stimulation have attracted much attention because of not only for basic research but also for wide applications. In particular, sensitive response to external stimulations including light can be extended in the cooperative system close to phase transition point. However, many previous works have focused mainly on organic strongly correlated electron systems. An exploration of new system for a photoinduced phase transition is important subject for further research progress. Recently, in the quantum paraelectric perovskites, SrTiO3 and KTaO3, an anomalous increase of dielectric constant has been observed as a new photoinduced cooperative phenomenon. In the present study we investigate extremely low frequency Raman spectra under UV excitation on perovskites and bismuth-layered perovskites to clarify the dynamical property on photoinduced cooperative phenomena of the quantum paraelectrics and ferroelectrics. In this study we obtained the followi … More ng conclusions.1. A perfect softening of the ferroelectric mode has been observed in the isotope-induced ferroelectric SrTi18O3 by a high-resolution technique using a Sandercock-type tandem Fabry-Perot interferometer. The mechanism of the phase transition is concluded to be an ideal displacive-type with perfect softening. From the difference between the soft mode behavior of quantum paraelectric SrTi16O3 and ferroelectric SrTi18O3, the photoinduced cooperative phenomenon observed in quantum paraelectrics should originate in a vibronic coupling between the ferroelectric soft mode and a photoinduced state.2. An appearance of new central peak related with a photoinduced state and an anomalous instability of the soft mode behavior were observed in layered perovskite oxides by the high-resolution light scattering technique. The obtained results are the first report of the Raman scattering spectra that indicate the existence of photoinduced state. Further systematical investigation using the high resolution light scattering technique will discover a new class of a quantum ferroelectric cooperative phenomenon. Less

相变及其通过外部刺激的控制不仅具有基础研究的意义，而且具有广泛的应用前景，特别是在接近相变点的协同系统中可以扩展对包括光在内的外部刺激的敏感响应。之前的许多工作主要集中在有机强相关电子系统上，探索新的光致相变系统是进一步研究进展的重要课题，最近，在量子顺电钙钛矿、SrTiO3和KTaO3中，介电常数出现了异常增加。被观察为一种新的光致协同现象。在本研究中，我们研究了钙钛矿和铋层状钙钛矿在紫外激发下的极低频拉曼光谱，以阐明量子顺电体和铁电体的光致协同现象的动力学特性。得到以下结论：1. 在同位素诱导的铁电 SrTi18O3 中观察到铁电模式的完美软化。利用桑德科克型串联法布里-珀罗干涉仪的高分辨率技术，根据量子顺电SrTi16O3 和铁电SrTi18O3 软模行为的差异，得出相变机制是理想的位移型。 ，在量子顺电体中观察到的光致协同现象应该起源于铁电软模和光致态之间的振动耦合。 2．通过高分辨率光散射技术在层状钙钛矿氧化物中观察到与光致态相关的中心峰和软模式行为的异常不稳定性，所获得的结果是拉曼散射光谱表明光致态存在的第一个报告。使用高分辨率光散射技术的进一步系统研究将发现一类新的量子铁电合作现象。

项目成果

Ferroelectric Phase Transition in Bi-Layered Perovskite Sr_2Bi_4Ti_5O_<18>

双层钙钛矿Sr_2Bi_4Ti_5O_<18>中的铁电相变

• 发表时间: 2007
• 期刊: Ferroelectrics 346
• 作者: M. Takesada;M. Itoh;A. Onodera;and T. Yagi;Masaki TAKESADA;Tadahiko ISHIKAWA;Seiko MOURI
• 通讯作者: Seiko MOURI

High Carrier Mobility Coupled With Quantum Paraelectric Fluctuation

高载流子迁移率与量子顺电涨落相结合

• 发表时间: 2007
• 期刊: Ferroelectrics 346
• 作者: T. Ishikawa;M. Kurita;S. Koshihara;M. Takesada;M. Itoh
• 通讯作者: M. Itoh

強誘電体Li-doped Zn0における光照射効果

光照射对铁电Li掺杂Zn0的影响

• 发表时间: 2007
• 作者: S. Kataoka;M. Takesada;A. Ueki;H. Nihonmatsu;and A. Onodera;福永正則
• 通讯作者: 福永正則

The Central Peak on Bismuth-Layered Perovskites, Ba_2Bi_4Ti_5O_18

铋层状钙钛矿的中心峰，Ba_2Bi_4Ti_5O_18

• 发表时间: 2008
• 作者: S. Kataoka;M. Takesada;A. Ueki;H. Nihonmatsu;and A. Onodera
• 通讯作者: and A. Onodera

"New Phase Transition in Layered Ferroelectric Pb_2Bi_4Ti_5O_<18>"

“层状铁电体 Pb_2Bi_4Ti_5O_<18> 中的新相变”

• 发表时间: 2007
• 期刊: Ferroelectrics 355
• 作者: Y.Nagai;M.Igashira;T.Takaoka;T.Kikuchi et al.;Masaki TAKESADA;Seiko MOURI
• 通讯作者: Seiko MOURI