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Photo-induced magnetic phase transition in spin crossover complexes

自旋交叉复合物中的光致磁相变

基本信息

批准号：
11215202
负责人：
MINAMI Fujio
金额：
$ 26.37万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research on Priority Areas (B)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

项目摘要

Photowithching process between low- and high-spin states in is investigated in spin crossover materials, such as spin crossover complexes and semimagnetic semiconductors. The outline of the achieved results is shown as follows.(1) Photo-induced magnetic phase transition in spin crossover complexesDetails of the photo-induced magnetic phase transition in Fe^<2+> spin crossover complexes were investigated by measuring absorption spectrum and magnetic susceptibility. In the photoswithing process between low- and high-spin states, nonlinear characteristics such as thresholdlike behavior, incubation period, and phase separation have been observed. These results demonstrate that the cooperative intersystem crossing mediated by spin-lattice interaction plays a key role in driving process of a new class of nonequilibrium phenomena. In addition, it turned out that this photo-induced magnetic phase transition process was greatly influenced by an external magnetic field.(2) Photo-induced magnetic phase transition in semimagnetic semiconductorsTime-resolved Magneto-photoluminescence experiments were carried out in a semimagnetic semiconductor Cd _<0.9>Mn_<0.1>Te with varing exciton density. A reduction of the Zeeman shift and the binding energy of magnetic polaron is observed. The spectral feature is interpreted by the heating effect of manganese spins. Polarization dependence of the spin heating is observed for the first time, revealing the contribution of spin flip between excitons and magnetic ions to the heating process.

研究了自旋交叉材料（如自旋交叉配合物和半磁半导体）中低自旋态和高自旋态之间的光吸收过程。所取得的成果概要如下。(1)自旋交叉配合物的光诱导磁相变通过测量Fe^<2+>自旋交叉配合物的吸收光谱和磁化率来研究其光诱导磁相变的细节。在低自旋态和高自旋态之间的光转换过程中，观察到类阈值行为、潜伏期和相分离等非线性特性。这些结果表明，由自旋-晶格相互作用介导的协同系统间交叉在一类新的非平衡现象的驱动过程中起着关键作用。此外，还发现这种光致磁相变过程受外加磁场的影响很大。(2)半磁半导体的光致磁相变在不同激子密度的半磁半导体材料Cd <0.9>Mn_<0.1>Te上进行了时间分辨磁光致发光实验。观察到磁性极化子的塞曼位移和结合能的减小。光谱特征可以用锰自旋的热效应来解释。首次观察到自旋加热的极化依赖性，揭示了激子和磁离子之间的自旋翻转对加热过程的贡献。