Comparative study of Weyl semimetal, topological and Chern insulators: thin-film point of view

TL;DR

This paper investigates the topological properties of thin films derived from 3D topological phases, comparing Weyl semimetals, Chern insulators, and topological insulators, and examines their robustness against disorder through numerical conductance studies.

Contribution

It provides a comparative analysis of thin-film topological phases, highlighting the relationships among Weyl semimetals, Chern insulators, and topological insulators, and tests their stability with disorder.

Findings

Weyl semimetals relate to Chern insulators as topological insulators relate to weak topological insulators.

Calculated topological indices for various thin-film models.

Conductance remains robust against disorder in studied systems.

Abstract

Regarding three-dimensional (3D) topological insulators and semimetals as a stack of constituent 2D topological (or sometimes non-topological) layers is a useful viewpoint. Primarily, concrete theoretical models of the paradigmatic 3D topological phases such as Weyl semimetal (WSM), strong and weak topological insulators (STI/WTI), and Chern insulator (CI), are often constructed in that way. Secondarily, fabrication of the corresponding 3D topological material is also done in the same spirit; epitaxial growth technique is employed, making the resulting sample in the form of a thin film. Here, in this paper we calculate $\mathbb{Z}$- and $\mathbb{Z}_2$-indices and study evolution of the topological properties of such thin films of 3D topological systems, making also a comparative study of CI- vs. TI-type models belonging to different symmetry classes in this respect. Through this comparative study we suggest that WSM is to CI as STI is to WTI. Finally, to test the robustness of our scenario against disorder and relevance to experiments we have also studied numerically the two-terminal conductance of the system using transfer matrix method.