Topological semimetal phases in HgTe-related alloys: Berryology and surface transport

拓扑非平凡半金属-狄拉克半金属和Weyl半金属-显示出有趣的性质：在体中有点状费米面，而在Weyl半金属的情况下，在表面有圆弧状开放费米面。我们预测，除了HgTe和HgS的琐碎和强拓扑绝缘体相外，HgTe1-xSx取代合金在应变方向上显示拓扑狄拉克半金属和Weyl半金属相，我们将进一步探索拓扑半金属的未知领域：其他类似HgTe和HgS的材料是否也表现出拓扑非琐碎半金属相？拓扑非平凡无序系统，特别是取代合金，如何进行拓扑表征？拓扑半金属相如何在表面敏感输运中表现出来？Weyl半金属，即费米弧的独特表面电子结构的具体特征是什么？此外，我们将继续研究磁修饰拓扑绝缘体，以确定表现出量子反常霍尔效应的系统。

Topological nontrivial semimetals - Dirac and Weyl semimetals - show intruiging properties: point-like Fermi surfaces in the bulk and at the surface arc-shaped open Fermi surfaces in the case of Weyl semimetals. Motivated by our prediction that - besides the established trivial and strong topological insulator phases of HgTe and HgS - HgTe1-xSx substitutional alloys show topological Dirac semimetal and Weyl semimetal phases upon strain along the [001] direction we will explore the unchartered territory of topological semimetals further:Do other materials similar to HgTe and HgS exhibit topological nontrivial semimetal phases?How can topological nontrivial disordered systems, in particular substitutional alloys, be topologically characterized?How do topological semimetal phases manifest themselves in surface-sensitive transport? What are specific signatures of the unique surface electronic structures of Weyl semimetals, i.e. the Fermi arcs?Furthermore, we will continue our work on magnetically modified topological insulators, to identify systems that exhibit a quantum anomalous Hall effect.