Thin films based on topological Heusler materials

我们联合提议的长期目标是通过生产可应用于自旋电子学工程的化合物，使正在开发的拓扑绝缘子研究领域更接近实际应用。这一目标意味着理论/表征合适材料、生长具有最佳传输性能的薄膜，以及最终生产组合器件之间的三个层次的合作。我们的基本材料来源将是立方半导体Heusler化合物家族，其中第一个拓扑非平凡系统已经被确定。Heusler家族是研究最多的多种材料类别之一，具有许多众所周知的性质和悠久的自旋电子学应用历史。将应用从头计算分析来选择合适的候选人。在这里，具有优化性能的材料是进一步薄膜生产的中心工作。将特别努力研究在多组分系统中经常发生的无序的影响。最后，将进行高级计算，以获得它们在真实表面和异质结构设置下的光谱和输运性质。这些信息将是指导该项目的实验部分所必需的，即高质量的薄膜生长和它们在最重要的标准方面的优化：在费米能量下Dirac表面态的稳定，最佳的掺杂(大多数Heusler半导体都是本征的p掺杂)，低载流子密度和高迁移率。所有项目合作伙伴在理论上与Heusler材料合作、薄膜生长和生产用于隧道结等器件的组合异质结构方面都有长期的经验。有效地结合在一起，确保了我们雄心勃勃的目标的成功，即开发用于拓扑绝缘体的新化合物，实现在薄膜和器件中的应用。

The long term goal of our combined proposal is to bring the developing research field of topological insulators closer to the real-life applications by producing the compounds, which can be applied in spintronics engineering. This goal implies a three-level collaboration between theory/characterization of suitable materials, growing thin films with optimized transport properties, and finally producing the combined devices. Our basic material source will be the family of cubic semiconducting Heusler compounds in which the first topologically-nontrivial systems were already identified. The Heusler family is one of the most studied diverse materials classes with many well-understood properties and long history in spintronics applications. The ab-initio analysis will be applied to select the suitable candidates. Here, materials with optimized properties for further thin films production are in the center of the work. Special effort will be put on the effects of disorder which often occur in multicomponent systems. Finally, advanced calculations will be performed to obtain their spectral and transport properties within the realistic surface and hetero-structure setup. This information will be necessary to guide the experimental part of the project, i.e. a high-quality growth of the thin films and their optimization with respect to the most important criteria: the stabilization of the Dirac surface states at the Fermi energy, optimal doping (most of the Heusler semiconductors are intrinsically p-doped), low carrier density and high mobility.All project co-partners have long-term experience by working with Heusler materials in theory, growth of thin films and production of combined hetero-structures for devices such as tunnel junctions. Being efficiently combined together this guarantees the success of our ambitious goal of developing new compounds for topological insulators, the realization in thin films and devices.