Solving the fundamental limitations for RT spintronics - the role of interfaces in electron spin detection and injection

传统半导体电子学中的电流由施加到任何特定电子元件的各个部分的电压控制。然而，一种控制电流流动的全新方法是在大约20年前提出的。这一新想法是基于这样的观察，即电子(自旋)的内部角动量及其相关的磁矩在纳米级距离内是守恒的。这就是说，当制备超薄层结构时，自旋在整个结构厚度上“记住”它的取向，这意味着具有不同自旋取向的电子不会独立地混合和流动，就像在两根平行连接的独立导线中一样。如果层结构包含磁性层，则两个自旋通道变得不等价。此外，还发现具有给定自旋取向的电子的电阻取决于层结构中所有磁性分量的磁组态。由于可以通过施加磁场来改变磁构型，所以可以通过施加磁场来控制电子(电流)的流动。随着这一发现，一个被称为自旋电子学的全新凝聚态物理领域的时代开始了。自旋电子学思想的成功应用依赖于我们生长超薄磁层结构的能力，这种结构在原子尺度上近乎完美。在过去的12个月里，对于含有铁磁性金属(FM)和氧化镁绝缘层的层结构已经实现了这一点。然而，对于包括FM层和半导体(SC)层的多层膜来说，这些理想的条件还没有被重新考虑。然而，自旋电子学未来的成功取决于自旋电子学组件与传统半导体结构的集成。这项建议的主要目标是将经典自旋电子学领域的实验专业知识，特别是在层结构外延生长方面的专业知识与研究具有氧化镁势垒的近完美磁性结所获得的理论见解相结合，我们相信，为具有氧化镁势垒的磁性结开发的实验和理论方法都可以转移到FM/SC系统中，从而解决在FM/SC界面上实现近乎完美的自旋输运的突出问题。

Electric current in conventional semiconductor electronics is controlled by a voltage applied to various parts of any particular electronic component. However, a completely new way of controlling the flow of electric current was proposed some twenty years ago. This new idea is based on the observation that the internal angular momentum of electrons (spin) with its associated magnetic moment is conserved over nanoscale distances. It follows that, when an ultrathin layer structure is prepared, the spin 'remembers' its orientation across the whole thickness of the structure, which means that electrons with different spin orientations do not mix and flow independently as if in two separate wires connected in parallel. If the layer structures contains magnetic layers the two spin channels become inequivalent. Moreoever, it is found that the resistance of electrons with a given spin orientation depends on the magnetic configuration of all the magnetic components in the layer structure. Since the magnetic configuration can be altered by applying a magnetic field, one can control the flow of electrons (electrical current) by applying a magnetic field. With this discovery the era of an entirely new field of condensed matter physics called spintronics had began. Successful applications of the ideas of spintronics depends on our ability to grow ultrathin magnetic layer structures which are near perfect on an atomic scale. Within the last twelve months this has been achieved for layer structures containing ferromagnetic metals (FM) and MgO insulating barrier. However, for multilayers contaning FM layers and semidoncuctor (SC) layers these ideal conditions have yet to be reasloed. Yet the future success of spintronics depends on integration of spintronic components into conventional semiconductor structures. The main goal of this proposal is to combine experimental expertise in the area of classical spintronics and, in particular, expertise in epitaxial growth of layer structures with theoretical insights gained from studying near perfect magnetic junctions with an MgO barrier, We are confident that both experimental and theoretical methods developed for magnetic junctions with an MgO barrier can be transferred to FM/SC systems and thus the outstanding problem of achieving near perfect spin transport across FM/SC interfaces can be solved.