Topological insulators are materials that are electrically insulating in the bulk but can conduct electricity due to topologically protected electronic edge or surface states. Since 2013, the German Research Foundation (DFG) has been supporting the Priority Program “Topological Insulators: Materials – Fundamental Properties – Devices” (SPP 1666) and in the time since, topological insulators developed from a mere curiosity to a material class that entered many fields of applied research. This Special Issue presents in 20 articles reports of the Priority Program reflecting its three areas of activity: (i) Understanding and improvement of existing topological insulator materials, regarding the size of the band gap and intrinsic doping levels, to enable room temperature applications, (ii) exploration of fundamental properties necessary for the development of device structures, and (iii) discovery of new materials to overcome deficits of current materials and explore new properties. See also the Guest Editorial (article number 2000594). The cover shows a Bi₂Te₃/MnBi₂Te₄ heterostructure, a ferromagnetic topological insulator (data by M. Albu, H. Groiss, S. Wimmer, G. Kothleitner, O. Caha, and J. Michalička; artwork by E. D. L. Rienks and O. Rader).

中文翻译：

---

拓扑绝缘子：材料–基本特性–器件

拓扑绝缘体是在整体上电绝缘但由于拓扑保护的电子边缘或表面状态而可以导电的材料。自2013年以来，德国研究基金会（DFG）一直在支持优先项目“拓扑绝缘子：材料–基本特性–器件”（SPP 1666），从那时起，拓扑绝缘子便从单纯的好奇心发展到了进入的材料类别应用研究的许多领域。本特刊在20篇文章中介绍了优先计划的报告，反映了其三个活动领域：（i）了解和改进现有的拓扑绝缘体材料，涉及带隙的大小和固有掺杂水平，以实现室温应用，（ii）探索开发器件结构所必需的基本特性，以及（iii）发现新材料以克服当前材料的不足并探索新特性。另请参见客座社论（文章编号2000594）。封面上有一张毕₂ Te ₃ / MnBi ₂ Te ₄异质结构，铁磁拓扑绝缘体（M. Albu，H。Groiss，S。Wimmer，G。Kothleitner，O。Caha和J.Michalička的数据； EDL Rienks和O. Rader的艺术品）。