Two-dimensional Topological Quantum Chemistry and Catalog of Topological Materials

TL;DR

This paper applies topological quantum chemistry to 2D materials, analyzing over 8,800 entries to identify topological phases, expanding the known library of 2D topological materials, and providing a public database and tools for further research.

Contribution

It adapts topological quantum chemistry to layer groups and creates a comprehensive catalog and tools for 2D topological materials analysis.

Findings

Identified 4,073 topologically non-trivial or obstructed insulators.

Expanded the library of known 2D topological materials.

Developed publicly available software for topology analysis.

Abstract

We adapt the topological quantum chemistry formalism to layer groups, and apply it to study the band topology of 8,872 entries from the computational two-dimensional (2D) materials databases C2DB and MC2D. In our analysis, we find 4,073 topologically non-trivial or obstructed atomic insulator entries, including 905 topological insulators, 602 even-electron number topological semimetals, and 1,003 obstructed atomic insulators. We thus largely expand the library of known topological or obstructed materials in two dimensions, beyond the few hundreds known to date. We additionally classify the materials into four categories: experimentally existing, stable, computationally exfoliated, and not stable. We present a detailed analysis of the edge states emerging in a number of selected new materials, and compile a Topological 2D Materials Database (2D-TQCDB) containing the band structures and detailed topological properties of all the materials studied in this work. The methodology here developed is implemented in new programs available to the public, designed to study the topology of any non-magnetic monolayer or multilayer 2D material.