Quantum Transport and the Aharonov-Casher Effect in Two Dimensional Electron Gases

这项研究的目的是通过实验证明，二维电子气中电子自旋的相位可以被操纵，以产生调制电导率的量子干涉效应；这种效应是由Aharonov和Casher在1984年预测的。在闪锌矿半导体中存在原子强度电场的情况下，利用二维受限电子气中的电子磁矩应该可以观察到Aharonov-Casher干涉。对于可实现的介观几何结构，诱导相移被预测为2-10pi弧度。环的几何形状和杨氏干涉仪将被定义在GSA异质结场效应装置上。通过电子磁矩与电子表面密度的关系，相将发生变化。在零磁场中观察到电子电导率的振荡，表面电子密度的周期性和量级为1/(25812)mhos，将证明Aharonov-Casher方法对于理解介观体系的自旋相关性质的有效性。这些实验将对预测电子自旋在半导体异质结中实现的量子点和弹道输运实验中所起的作用至关重要。电子在半导体固体中的输运原理已经被理解很久了。在过去的十年里，当制作非常小的器件结构时，已经观察到了说明电子波纹的干涉效应。这些大小需要是电子波长的数量级，大约是十万分之一米。这些量子器件的制造技术源于计算机芯片行业对越来越小的器件的要求。电子还携带一个磁矩，它可以表示为一个自旋量子数的物理可观测值。提出的这项研究是为了寻找操纵电子波的自旋相位的方法，例如引起干扰。当磁矩通过电场时，自旋相会发生变化。这里将利用化合物半导体中存在的内部电场。这项研究的结果将有助于理解电子自旋在异质结和类似量子器件结构中实现的量子点和弹道输运实验中的作用。

The objective of this research is to show experimentally that the phase of the electron spin in a two dimensional electron gas can be manipulated to produce quantum interference effects modulating the electrical conductivity; this effect was predicted by Aharonov and Casher in 1984. With the atomic strength electric fields present in zincblende semiconductors, the Aharonov-Casher interference should be observable using the electron magnetic moment in a two dimensionally confined electron gas. The induced phase shift is predicted to be 2-10 pi radians for realizable mesoscopic geometries. Ring geometries and Young interferometers will be defined on GsAs heterojunction field effect devices. The phase will be varied through the dependence of the electron magnetic moment upon electron surface density. In zero magnetic field the observation of oscillations in the electron conductivity, periodic in surface electron density and of magnitude 1/(25812) mhos, will demonstrate the validity of the Aharonov-Casher approach to the understanding of the spin dependent properties of mesoscopic systems. These experiments will be essential for predicting the role that electron spin plays in quantum dot and ballistic transport experiments implemented in semiconductor heterojunctions. %%% The principles of electron transport in semiconducting solids have been understood for a long time. In the last decade, interference effects illustrative of the wavenature of the electron have been observed when very small device structures are made. These sizes need to be of the order of the electron wavelength, about one ten millionth of a meter. The fabrication technology for these quantum devices originated in the requirements for ever smaller devices in the computer chip industry. The electron also carries a magnetic moment which can be represented as the physical observable of a spin quantum number. The research proposed is to search for methods to manipulate the spin phase of the electron waves such as to cause interference. Spin phase can change as the magnetic moment moves through an electric field. Here the internal electric fields existent in compound semiconductors will be exploited. The results of this research will assist in understanding the role of electron spin in quantum dot and ballistic transport experiments implemented in heterojunctions and similar quantum device structures.