Topological insulators (TIs) are of particular interest in the recent solid‐state research because of their exceptional features stemming from the conducting, topologically protected surface states. The exotic properties include the occurrence of novel quantum phenomena and make them promising materials for spintronics and quantum computing applications. Theoretical studies have provided a vast amount of valuable predictions and proposals, whose experimental observation and implementation, to date, are often hindered by an insufficient sample quality. The effect of even a relatively low concentration of defects can make the access to purely topological surface states impossible. This points out the need of high‐quality bulk‐insulating materials with ultra‐clean surfaces/interfaces, which requires sophisticated sample/device preparations as well as special precautions during the measurements. Herein, the challenging work on 3D TI thin films with a focus on ${\text{Bi}}_2{\text{Te}}_3$ is reported. It covers the optimization of the molecular beam epitaxy growth process, the in situ characterization of surface states and transport properties, the influence of exposure to ambient gases and of capping layers, as well as the effect of interfacing TI thin film with magnetic materials.

中文翻译：

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拓扑绝缘子研究的挑战：Bi2Te3薄膜和磁性异质结构

拓扑绝缘体（TIs）在近期的固态研究中特别受关注，因为它们具有导电，受拓扑保护的表面状态的特殊功能。奇异的特性包括出现新的量子现象，使其成为自旋电子学和量子计算应用的有希望的材料。理论研究已经提供了大量有价值的预测和建议，迄今为止，其实验观察和实施常常受到样品质量不足的阻碍。即使缺陷浓度相对较低，也无法访问纯拓扑表面状态。这指出了需要具有超净表面/界面的高质量块状绝缘材料，这需要复杂的样品/设备准备以及测量过程中的特殊预防措施。在此，针对3D TI薄膜的具有挑战性的工作重点是${\text{双}}_2{\text{特}}_3$被报道。它涵盖了分子束外延生长过程的优化，表面状态和传输特性的原位表征，暴露于环境气体和覆盖层的影响以及TI薄膜与磁性材料的连接作用。