A Spin Interference Device

自旋干涉器件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金属和半导体中载流子的自旋来实现新的电子器件。 在这样的设备中，关键的重要性是自旋和自旋电流的产生、操纵和检测。 一个例子是自旋FET（场效应晶体管），一种开关器件，其工作原理是将自旋极化载流子注入沟道，通过外部电场（栅极偏置）操纵（通过旋进旋转）它们的自旋，以及在漏极对载流子进行自旋敏感检测。 如果成功的话，这种对自旋的操纵也会对另一个新兴的、甚至更奇特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主要候选者。本项目的目标是演示实现自旋器件，它有点类似于自旋FET，但具有简化的优点，它不需要注入或检测自旋极化载流子。 该装置本质上是一个Aharanov-Bohm环，由一个具有强大和可调的自旋轨道相互作用的二维（2D）载体系统制成。它的运作依赖于顺时针和逆时针自旋波函数之间的干涉。 干涉，因此环的电导，可以通过调节自旋-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。它还需要具有可调自旋轨道相互作用的高质量2D载体系统。 调制掺杂GaAs/AlGaAs异质结构中的2D空穴为该项目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106 cm 2/Vs，并且它们的自旋-轨道相互作用的可调谐性最近已被证明。

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.