A STUDY OF INTERACTIONS BETWEEN ELEMENTARY EXCITATIONS IN TRANSITION METAL OXIDES BY MEANS OF FEMTOSECOND SPECTROSCOPY

过渡金属氧化物中基本激发之间相互作用的飞秒光谱研究

基本信息

批准号：
07454063
负责人：
NAKAMURA Arao
金额：
$ 5.12万
依托单位：
NAGOYA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

项目摘要

We have investigated change in electronic states by photodoping with femtosecond pulses and relaxation dynamics of photoexcited states in 3d transition metal oxides in order to elucidate interactions with phonons and magnons and relaxation processes characteristic of magnetic phases.i) Relaxation dynamics of electronic states in CuO2 planes in cuprates. We have observed the photoinduced spectral change which is interpreted by the carrier doping effect by optical excitations. Optically induced in-gap states are relaxd in about 1 ps by emission of magnons, which indicates a crucial role of magnetic excitations in strongly correlated system.ii) Preparation of 3d transition metal oxides films. Using a laser ablation technique we have fabricated many kind of oxides films.Choosing an appropriate substrate temperature depending on materials we can fabricate transition metal oxides films such as cobaltates, nicklates and manganates.iii) Optical spectra and relaxation dynamics associated with magnetic transitions. Temperature dependence of absorption spectra for thin films of double-exchange ferromagnet R0.6S_r0.4Mn03 has been investigated with variation of the one-electron band width. We have found that optical excitations in the visible region strongly couples with the local spin alignments in these doped manganates. Furthermore, we have investigated ultrafast spectral change induced by femtosecond pulse excitations. The femtosecond pulse doping induces change in local spin alignments and the paramagnetic domain is formed in 200 ps and this domain is converted into the ferromagnetic domain in about 100 ns. This is the first observation of dynamical behaviors of spins and local spin alignments in strongly correlated systems and demonstrates the controllability of the spin systems by means of irradiation of visible light. This may lead us to apply these materials to magneto-optical devices with a photon-mode.

我们已经通过与飞秒脉冲进行光电处理和3D过渡金属氧化物中光激发状态的松弛动力学进行了调查，以阐明与磁性阶段的相互作用，以及磁性阶段的特征。在丘比特。我们已经观察到光诱导的光谱变化，这是通过光激发载体掺杂效应来解释的。光学诱导的间隙状态在大约1 ps中通过发射通过发射，这表明磁激发在密切相关的系统中至关重要。II）制备3D过渡金属氧化物膜的制备。使用激光消融技术，我们制造了许多类型的氧化物膜。根据材料，选择适当的底物温度，我们可以制造过渡金属氧化物膜，例如钴体，镍和锰酸盐。IIII。双交换Ferromagnet R0.6S_R0.4MN03的吸收光谱的温度依赖性已随着单电子带宽度的变化进行了研究。我们发现，在这些掺杂的锰酸盐中，可见区域的光激发与局部自旋比对。此外，我们研究了飞秒脉冲激发引起的超快光谱变化。飞秒脉冲掺杂会诱导局部自旋比对变化，并且在200 ps中形成顺磁性结构域，该结构域在约100 ns中转换为铁电磁域。这是对密切相关系统中旋转和局部自旋对齐的动态行为的第一个观察，并通过辐照可见光来证明自旋系统的可控性。这可能会导致我们将这些材料应用于带有光子模式的磁光设备。