A Spin Interference Device

自旋干涉器件摘要自旋电子学是固体科学与工程中的一个新兴领域。它的广泛目标是利用载流子在金属和半导体中的自旋来实现新型电子设备。在这种装置中，最重要的是自旋和自旋流的产生、操作和检测。一个例子是自旋场效应晶体管(Spin-FET)，这是一种开关器件，其操作基于将自旋极化的载流子注入沟道，通过外部电场(栅极偏置)操纵(通过进动旋转)自旋，以及对漏极处的载流子进行自旋敏感检测。如果成功，这种对自旋的操纵也可能对另一个新兴的、或许更具异国情调的量子计算领域产生影响，因为自旋是拟议中的量子计算机中量子信息比特的领先候选者。这个项目的目标是展示一种自旋器件的实现，它在某种程度上类似于自旋场效应管，但具有不需要注入或检测自旋极化载流子的简化优势。该器件本质上是一个由二维(2D)载流子系统组成的Aharanov-Bohm环，具有强烈且可调的自旋-轨道相互作用。它的运行依赖于顺时针和逆时针自旋波函数之间的干涉。干涉以及环的电导可以由调整自旋-轨道相互作用的栅电极来调制。该项目结合了最先进的纳米技术和仔细的运输测量。它还需要高质量的2D载流子系统，具有可调的自旋-轨道相互作用。调制掺杂的GaAs/AlGaAs异质结中的2D空穴为这一计划提供了一个近乎理想的系统；它们具有非常高的低温迁移率，约为106cm2/vs，并且它们的自旋-轨道相互作用的可调性最近被证明。

A Spin Interference DeviceAbstract Spintronics is an emerging area in solid state science and engineering. Its broad goal is to utilize carriers' spin in metals and semiconductors to realize novel electronic devices. In such devices, of key importance are the creation, manipulation, and detection of spin and spin-currents. An example is the spin-FET (field-effect transistor), a switching device whose operation is based on the injection of spin-polarized carriers into the channel, manipulation (rotation via precession) of their spin via an external electric field (gate bias), and the spin-sensitive detection of the carriers at the drain. If successful, such manipulation of spins can also have impact on another emerging, and perhaps even more exotic, field of quantum computing, as spin is the leading candidate for the quantum bit of information in the proposed quantum computers. The goal of this project is demonstrate the realization of a spin device which is somewhat similar to the spin-FET but has the simplifying advantage that it does not require the injection or detection of spin-polarized carriers. The device is essentially an Aharanov-Bohm ring made of a two-dimensional (2D) carrier system with a strong and tunable spin-orbit interaction. Its operation relies on the interference between the clockwise and counter-clockwise travelling spin wave functions. The interference, and therefore the conductance of the ring, can be modulated by a gate electrode which tunes the spin-orbit interaction. The project combines state-of-the art nanotechnology and careful transport measurements. It also requires a high-quality 2D carrier system with tunable spin-orbit interaction. The 2D holes in modulation-doped GaAs/AlGaAs heterostructures provide a nearly ideal system for this project; they have very high low-temperature mobility, of the order of 106 cm2/Vs, and the tunability of their spin-orbit interaction has recently been demonstrated.