论文标题
旋转轨道耦合纳米线中的限制与接口绑定状态
Confinement versus interface bound states in spin-orbit coupled nanowires
论文作者
论文摘要
半导体纳米线具有强烈的Rashba旋转轨道耦合，目前正处于几个研究领域的焦点，例如Spintronics，拓扑材料和量子计算。尽管大多数理论模型都假定无限长的纳米线，但在实际的实验设置中，纳米线具有有限的长度，可以与金属电极接触，并部分被门覆盖。通过通过不均匀的自旋轨道耦合曲线来考虑这些效果，我们表明，在纳米线中，总体上出现了两种类型的结合状态，即限制状态和界面结合状态。与纳米线的有限长度有关的限制状态的出现受到表征铅和纳米线的散装带底部的不匹配而受到青睐，甚至在没有磁场的情况下也会发生。相反，仅当磁场垂直于自旋轨道场方向施加磁场时，才能出现界面绑定状态，并克服了临界值，并且受到界面上两个区域的频带底部的对齐的青睐。我们详细描述了这两种绑定状态的出现，指出了它们的差异。此外，我们表明，当纳米线部分被门覆盖时，磁场的应用可以将电子基态的性质从限制变为界面结合状态，从而确定电子电荷的重新分布。
Semiconductor nanowires with strong Rashba spin-orbit coupling are currently on the spotlight of several research fields such as spintronics, topological materials and quantum computation. While most theoretical models assume an infinitely long nanowire, in actual experimental setups the nanowire has a finite length, is contacted to metallic electrodes and is partly covered by gates. By taking these effects into account through an inhomogeneous spin-orbit coupling profile, we show that in general two types of bound states arise in the nanowire, namely confinement bound states and interface bound states. The appearance of confinement bound states, related to the finite length of the nanowire, is favoured by a mismatch of the bulk band bottoms characterizing the lead and the nanowire, and occurs even in the absence of magnetic field. In contrast, an interface bound states may only appear if a magnetic field applied perpendicularly to the spin-orbit field direction overcomes a critical value, and is favoured by an alignment of the band bottoms of the two regions across the interface. We describe in details the emergence of these two types of bound states, pointing out their differences. Furthermore, we show that when a nanowire portion is covered by a gate the application of a magnetic field can change the nature of the electronic ground state from a confinement to an interface bound state, determining a redistribution of the electron charge.
