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

传统半导体电子器件中的电流由施加到任何特定电子部件的各个部分的电压控制。然而，大约20年前，有人提出了一种全新的控制电流的方法。这个新想法是基于观察到电子的内部角动量（自旋）及其相关的磁矩在纳米尺度的距离上是守恒的。因此，当制备多层结构时，自旋会记住其在整个结构厚度上的取向，这意味着具有不同自旋取向的电子不会像在两个并联连接的单独导线中那样独立混合和流动。如果层结构包含磁性成分，则两个自旋通道变得不等效。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组分的磁性构型。由于磁场可以改变磁结构，人们可以通过施加磁场来控制电子（电流）的流动。随着这一发现，一个全新的凝聚态物理学领域--自旋电子学的时代开始了。自旋电子学思想的成功应用取决于我们在原子尺度上生长出近乎完美的磁性层结构的能力。在过去的十二个月里，包含铁磁金属（FM）和MgO绝缘屏障的层结构已经实现了这一目标。然而，对于包含FM和半导体（SC）层的多层膜，这些理想条件尚未实现。然而，自旋电子学未来的成功取决于将自旋电子元件集成到传统的半导体结构中。该提案的主要目标是将联合收割机在经典自旋电子学领域的实验专业知识，特别是在层结构的外延生长方面的专业知识与从研究具有MgO阻挡层的接近完美的磁性结中获得的理论见解相结合。我们有信心，实验和理论方法开发的磁性结与MgO屏障可以转移到FM/SC系统，从而实现近完美的跨FM/SC界面的自旋输运的突出问题可以得到解决。

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 structure contains magnetic components the two spin channels become inequivalent. Moreover, 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 an applied magnetic field, one can control the flow of electrons (electric current) by applying a magnetic field. With this discovery the era of an entirely new field of condensed matter physics called spintronics had begun.Successful application of the ideas of spintronics depends on our ability to grow ultrathin magnetic layer structures that 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 containing FM and semiconductor (SC) layers these ideal conditions have not yet been realised.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 insight gained from studying near perfect magnetic junctions with MgO barrier. We are confident that both experimental and theoretical methods developed for magnetic junctions with 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.