Quantum kinetic theory of ultrafast phenomena in diluted magnetic semiconductors

稀磁半导体中超快现象的量子动力学理论

基本信息

批准号：
263274142
负责人：
Professor Dr. Vollrath Martin Axt
金额：
--
依托单位：
Lehrstuhl für Theoretische Physik III (Quantentheorie der kondensierten Materie)
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2014
资助国家：
德国
起止时间：
2013-12-31 至 2014-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/263274142?language=en
关键词：
Quantum kinetic theory ultrafast phenomena

项目摘要

This project is devoted to theoretical studies of ultrafast phenomena in diluted magnetic semiconductor (DMS) which are targeted at advancing the understanding of basic physical processes in DMS such as spin and orbital-angular-momentum transfer on ultrafast time scales. We aim to identify quantum-kinetic mechanisms that are of interest for advanced technological applications, e.g., the coherent control of magnetic properties on short times. The specific objectives of the project are three-fold. First, to elucidate the competition of the spin-orbit interaction with RKKY-type exchange interactions in the spin transfer between free carriers and magnetic impurities. Second, to explore the coherent quantum control possibilities brought about by excitation with light with orbital angular momentum (twisted light) and intense single-cycle terahertz pulses. And finally, to investigate the role of the electron-electron interaction in the decoherence processes that limit the coherent manipulation of angular-momentum transfer in DMS. The methodic starting point is a recently developed quantum kinetic density matrix description of the exchange induced spin-transfer in DMS. This theory shall be extended to include additionally the spin-orbit and electron-electron interaction as well as the coupling to twisted light. If in the course of the project it turns out to be necessary, also non-equilibrium Green's function techniques may be used. The applicability of the newly developed extended equations shall be demonstrated by numerical studies that reveal the physical implications and allow for a comparison of the predictions with realistic (existing or proposed) experimental situations.

该项目致力于稀磁半导体（DMS）中超快现象的理论研究，旨在增进对DMS基本物理过程的理解，例如超快时间尺度上的自旋和轨道角动量转移。我们的目标是确定对先进技术应用感兴趣的量子动力学机制，例如短时间磁特性的相干控制。该项目的具体目标有三个。首先，阐明自由载流子与磁性杂质之间自旋转移中自旋轨道相互作用与RKKY型交换相互作用的竞争。其次，探索轨道角动量光（扭曲光）和强烈的单周期太赫兹脉冲激发所带来的相干量子控制的可能性。最后，研究电子-电子相互作用在退相干过程中的作用，该过程限制了 DMS 中角动量传递的相干操作。方法的起点是最近开发的 DMS 中交换诱导自旋转移的量子动力学密度矩阵描述。该理论应扩展到包括自旋轨道和电子-电子相互作用以及与扭曲光的耦合。如果在项目过程中证明有必要，也可以使用非平衡格林函数技术。新开发的扩展方程的适用性应通过数值研究来证明，数值研究揭示物理含义并允许将预测与现实（现有或提议的）实验情况进行比较。