Thin films based on topological Heusler materials

我们联合提出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，使拓扑绝缘体的发展研究领域更接近实际应用。这一目标意味着合适材料的理论/表征，生长具有优化输运特性的薄膜，以及最终生产组合器件之间的三级合作。我们的基本材料来源将是立方半导体赫斯勒化合物家族，其中第一个拓扑非平凡系统已经被确定。Heusler家族是研究最多的不同材料类别之一，具有许多众所周知的特性和自旋电子学应用的悠久历史。将采用从头算分析来选择合适的候选人。在这里，具有进一步薄膜生产优化性能的材料是工作的中心。特别的努力将放在混乱的影响，往往发生在多组分系统。最后，将进行高级计算，以获得它们在实际表面和异质结构设置下的光谱和输运性质。这些信息对于指导项目的实验部分是必要的，即薄膜的高质量生长及其在最重要标准方面的优化：狄拉克表面态在费米能量下的稳定，最佳掺杂（大多数Heusler半导体本质上是p掺杂），低载流子密度和高迁移率。所有项目合作伙伴都有长期从事Heusler材料理论，薄膜生长和隧道结等设备组合异质结构生产的经验。有效地结合在一起，这保证了我们开发用于拓扑绝缘体的新化合物，在薄膜和器件中实现的雄心勃勃的目标的成功。

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.