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Band Structure and Transport in Low-Dimensional Semiconductor Hole Systems

低维半导体空穴系统中的能带结构和输运

基本信息

批准号：
336985961
负责人：
Dr. Paul Thomas Wenk
金额：
--
依托单位：
Departamento de Nanoestructuras
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 2020-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/336985961?language=en
关键词：
Band Structure Transport Low Dimensional

项目摘要

The past years have witnessed an enormously increasing interest regarding spin-orbit coupling (SOC) in two-dimensional (2D) semiconductor systems. The present project focuses in particular on hole-systems which are special for several reasons. On the one hand, the large effective mass of holes compared to conduction band electrons diminishes the kinetic term such that contributions from SOC become more important; thereby, the SOC can be strong compared to n-type systems. On the other hand, the p-wave character of the heavy (HH) and light hole (LH) states reduces the hyperfine interaction of the carrier spin with the nuclei. This allows for long spin relaxation(SR)/dephasing times. All these features facilitate a very effective manipulation of carrier spins. This proposal is about studying different challenging aspects of p-type systems. One of them is the analysis of SR of carries in strained zinc-blende (ZB) type and wurtzite (WZ) type hole system. The goal is to minimize this SR or even find persistent spin states, in respect of building spintronics applications. Recently, we supplied proof for the existence of a persistent spin helix and the needed conditions in 2D ZB electron systems for most general growth directions of the semiconductor heterostructure. Inspired by this findings, we would like to answer the question, whether spin preserving symmetries in 2D hole gases (2DHG) also arise in systems with growth directions other than [001]. The analysis of SR is directly linked to the conduction properties in such a 2DHG which will be approached by calculating weak (anti)localization (WL/WAL). The WL/WAL has proved to be one important tool for probing SOC in experiments. The analysis will take into account the full symmetry of the SO field, going beyond the theory by Pikus et al. or Iordanskii et al. To have a clear understanding of the link between WL/WAL and SR, magnetoconductivity has to be studied. This brings us to the next nontrivial question to be answered in this project, namely, how the effective g-factor in the Zeeman term looks like if we consider SOC effects and confinement. Furthermore, since the g-factor strongly depends on the HH-LH subband splitting, it is important to comprise strain effects, which significantly influence the energy spacing. Further directions of work include the study of Zitterbewegung in hole systems including strain and linear in k Dresselhaus SOC terms for the 2DHG which have been neglected so far but have been shown recently to be significant. The wave packet dynamics will be simulated in realistic sample geometries. The developed models to be used will also take account of heterostructure interfaces which can cause dominant contributions to HH spin splitting as recently shown by Durnev et al.

在过去的几年里，人们对二维（2D）半导体系统中的自旋-轨道耦合（SOC）的兴趣极大地增加。本项目特别侧重于孔系统，这是特殊的几个原因。一方面，与导带电子相比，空穴的大有效质量减少了动力学项，使得来自SOC的贡献变得更重要;因此，SOC与n型系统相比可以更强。另一方面，重空穴（HH）和轻空穴（LH）态的p波特性降低了载流子自旋与原子核的超精细相互作用。这允许长的自旋弛豫（SR）/失相时间。所有这些特征有助于非常有效地操纵载流子自旋。这个提议是关于研究p型系统的不同挑战性方面。其中之一是对应变锌钛矿（ZB）型和纤锌矿（WZ）型空穴系统中载流子的SR进行了分析。我们的目标是最小化这个SR，甚至找到持久的自旋态，在建设自旋电子学应用方面。最近，我们提供了一个持久的自旋螺旋的存在的证明和所需的条件，在二维ZB电子系统的半导体异质结构的最一般的生长方向。受这一发现的启发，我们想回答这个问题，是否在二维空穴气体（2DHG）中的自旋保持对称性也出现在生长方向不是[001]的系统中。SR的分析直接关联到这样的2DHG中的传导特性，其将通过计算弱（反）局部化（WL/WAL）来接近。WL/WAL已被证明是一个重要的工具，在实验上探测SOC。分析将考虑到完全对称的SO场，超越了Pikus等人或Iordanskii等人的理论。为了清楚地了解WL/WAL和SR之间的联系，必须研究磁导率。这将我们带到了本项目中要回答的下一个重要问题，即，如果我们考虑SOC效应和约束，塞曼项中的有效g因子是什么样子的。此外，由于g因子强烈地依赖于HH-LH子带分裂，因此重要的是包括应变效应，其显著地影响能量间隔。进一步的工作方向包括Zitterbewegung孔系统的研究，包括应变和线性在k Dresselhaus SOC条款的2DHG已被忽视，但最近已被证明是显着的。波包动力学将在现实的样品几何形状进行模拟。所开发的模型也将考虑异质结界面，这可能会导致主导贡献HH自旋分裂最近所示的Durnev等人。

项目成果

期刊论文数量（6）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Ultralong spin lifetimes in one-dimensional semiconductor nanowires

DOI：
10.1063/1.5096970
发表时间：
2018-09
期刊：
Applied Physics Letters
影响因子：
4
作者：
F. Dirnberger;M. Kammermeier;J. Konig;M. Forsch;P. E. F. Junior;T. Campos;J. Fabian;J. Schliemann;C. Schuller;T. Korn;Paul Thomas Wenk;D. Bougeard
通讯作者：
F. Dirnberger;M. Kammermeier;J. Konig;M. Forsch;P. E. F. Junior;T. Campos;J. Fabian;J. Schliemann;C. Schuller;T. Korn;Paul Thomas Wenk;D. Bougeard

Driven Hofstadter butterflies and related topological invariants

驱动霍夫施塔特蝴蝶和相关拓扑不变量