Exciton spin dynamics in diluted magnetic semiconductor quantum wells

稀磁半导体量子阱中的激子自旋动力学

基本信息

批准号：
316976768
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：
2016
资助国家：
德国
起止时间：
2015-12-31 至 2019-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/316976768?language=en
关键词：
Exciton spin dynamics diluted magnetic

项目摘要

In this project we aim to develop a microscopic, quantum-kinetic theory for the spin dynamics in diluted magnetic semiconductor nanostructures accounting for both, correlations due to the exchange coupling with magnetic dopants as well as the Coulomb interaction, which in particular gives rise to excitonic correlations. The considered technologically important systems are especially promising in terms of innovative applications based on the active use of correlations and quantum coherent dynamical phenomena. This applies in particular to applications in information technology that require a coherent spin control. The basis for future progress in this direction is a deepened understanding of spin dynamics which requires a theory beyond the current state-of-the-art. As a first application of our new theory we shall try to identify quantum kinetic signatures in the spin dynamics of excitonic excitations in quantum wells. These studies will advance the understanding of spin relaxation and should provide insight concerning the role of quantum coherences for spin relaxation. In particular, we shall explore in how far the spin relaxation deviates from an incoherent process that can be modelled by rate equations. In this context we shall also analyze the impact of energetic redistributions between different excitonic states on the spin dynamics.A further focus of the research within this project is the analysis of the interplay between influences of the exchange interaction with magnetic dopants and the spin-orbit coupling of optically excited carriers on the spin dynamics. In diluted magnetic semiconductors usually the exchange interaction dominates. However, varying suitable material parameters in particular in multi-component composite semiconductors allows for tailoring the relative strengths of these interactions in a wide range. Even situations where both couplings are of comparable strength can be realized. Studies of excitations of free carriers in the latter regime give rise to the expectation that also in the case of excitonic excitations a qualitatively new dynamical behavior of the spin system should arise when both couplings are comparable. This could pave the way towards new approaches of spin control.Another target is to explore the possibilities to control the spin dynamics by exciting excitonic states using light with well-defined orbital angular momentum ('twisted light'). This part of the project shall shed light on the question whether the use of novel types of light sources, such as twisted light, that are a focus of topical research opens new ways for the external manipulation of spins that differ from traditional methods as, e. g., the spin orientation via circularly polarized conventional laser light.

在该项目中，我们旨在开发一种微观的量子 - 运动理论，用于稀释的磁性半导体纳米结构中的自旋动力学，这两者都会考虑两者的相关性，这是由于与磁性掺杂剂以及库仑相互作用耦合而引起的相关性，这尤其引起了兴奋性相关性。根据具有积极使用相关性和量子相干动力学现象的创新应用，被认为具有技术重要的系统在创新应用方面特别有希望。这特别适用于需要连贯旋转控制的信息技术应用程序。朝这个方向发展的未来进步的基础是对旋转动态的深入了解，这需要一个超出当前最新技术的理论。作为我们新理论的第一个应用，我们将尝试在量子井中激发激发的自旋动力学中识别量子动力学特征。这些研究将提高对自旋松弛的理解，并应提供有关量子相干在自旋松弛方面的作用的见解。特别是，我们将探索自旋松弛与可以通过速率方程式建模的不连贯过程的偏差。在这种情况下，我们还将分析不同激子状态之间的能量再分配对旋转动力学的影响。该项目内的研究的进一步重点是分析与磁性掺杂剂的交换相互作用与旋转轨道耦合在旋转动力学上的旋转轨道偶联的影响之间的相互作用。在稀释的磁半导体中，交换相互作用通常主导。但是，在多组分复合半导体中，尤其是在合适的材料参数中变化，可以在较大范围内调整这些相互作用的相对强度。即使是两个耦合都具有可比强度的情况也可以实现。对后一种状态中自由载体激发的研究引起了人们的期望，即在激发激发的情况下，当两个耦合都是可比性时，自旋系统的定性动力学行为也应出现。这可以铺平旋转控制方法的新方法。另一个目标是通过使用具有明确定义的轨道角动量（“扭曲的光”）的光（“扭曲光”）的光（“扭曲的光”）来探索通过激发激动的激发激发态态来控制旋转动力学的可能性。该项目的这一部分应阐明以下问题，即使用新型光源（例如扭曲光）的焦点是否为局部研究的重点开辟了新的方法，用于外部操纵与传统方法不同的旋转。 g。，通过循环极化的常规激光光的自旋取向。