Engineering two-dimensional kagome topological insulator from porous graphene

TL;DR

This paper reports the design of a metal-free, carbon-based 2D kagome topological insulator created by patterning porous graphene, achieving topological states at the Fermi level without doping, and highlighting its unique electronic properties.

Contribution

The study introduces a novel porous graphene-based kagome lattice that exhibits topological insulating behavior without metal atoms or doping, using intrinsic spin-orbit coupling considerations.

Findings

Achieves Fermi level alignment with Dirac point without doping.

Displays distinctive band structures with Dirac and flat bands.

Exhibits topological edge states in ribbon structures.

Abstract

Our study sets forth a carbon based two-dimensional (2D) kagome topological insulator without containing any metal atoms, that aligns the Fermi level with the Dirac point without the need for doping, overcoming a significant bottleneck issue observed in 2D metal-organic frameworks (MOFs)-based kagome structures. Our 2D kagome structure formed by creating patterned nano pores in the graphene sheet, nomenclatured as porous graphene-based kagome lattice (PGKL), is inspired by the recent bottom-up synthesis of similar structures. Because of absence of mirror symmetry in our porous graphene, by considering only first nearest neighbour intrinsic spin-orbit coupling (ISOC) within the tight-binding model unlike mostly used next nearest neighbour ISOC in the Kane-Mele model for graphene, PGKL exhibits distinctive band structures with Dirac bands amidst flat bands, allowing for the realization of topological states near the Fermi level. Delving into Berry curvature and Chern numbers provides a comprehensive understanding of the topological insulating properties of PGKL, offering valuable insights into 2D topological insulators. Analysis of the 1-D ribbon structure underscores the emergence of topological edge states.