Marsal Quentin, Varjas Dániel, Grushin Adolfo G
Université Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, 38000 Grenoble, France.
QuTech, Delft University of Technology, 2600 GA Delft, The Netherlands.
Proc Natl Acad Sci U S A. 2020 Dec 1;117(48):30260-30265. doi: 10.1073/pnas.2007384117. Epub 2020 Nov 18.
Amorphous solids remain outside of the classification and systematic discovery of new topological materials, partially due to the lack of realistic models that are analytically tractable. Here we introduce the topological Weaire-Thorpe class of models, which are defined on amorphous lattices with fixed coordination number, a realistic feature of covalently bonded amorphous solids. Their short-range properties allow us to analytically predict spectral gaps. Their symmetry under permutation of orbitals allows us to analytically compute topological phase diagrams, which determine quantized observables like circular dichroism, by introducing symmetry indicators in amorphous systems. These models and our procedures to define invariants are generalizable to higher coordination number and dimensions, opening a route toward a complete classification of amorphous topological states in real space using quasilocal properties.
非晶态固体仍处于新拓扑材料的分类和系统发现之外,部分原因是缺乏易于进行解析处理的现实模型。在此,我们引入了拓扑韦尔-索普模型类别,其定义在具有固定配位数的非晶晶格上,这是共价键合非晶态固体的一个现实特征。它们的短程性质使我们能够解析预测能隙。它们在轨道置换下的对称性使我们能够通过在非晶系统中引入对称性指标来解析计算拓扑相图,而拓扑相图可确定诸如圆二色性等量子化可观测量。这些模型以及我们定义不变量的程序可推广到更高的配位数和维度,为利用准局域性质对实空间中的非晶拓扑态进行完整分类开辟了一条道路。