Coexistence of flat bands and Dirac bands in a carbon-Kagome-lattice family

TL;DR

This paper reports the discovery of a family of three-dimensional carbon-Kagome-lattice structures where flat and Dirac bands coexist, potentially enabling superconductivity, supported by first-principles calculations and tight-binding models.

Contribution

It introduces a new family of carbon-based structures with coexisting flat and Dirac bands, analyzed through first-principles and tight-binding models, highlighting their potential for superconductivity.

Findings

Coexistence of flat and Dirac bands in CKL structures.

Flat bands originate from Kagome lattice orbital interactions.

Dirac bands are related to carbon zigzag chains.

Abstract

The Dirac bands and flat bands are difficult to coexist because they represent two extreme ends of electronic properties. However, in this paper, we propose a carbon-Kagome-lattice (CKL) family based on first-principles calculations, and the coexistence of Dirac and flat bands are observed in this series of three-dimensional carbon structures. The flat bands are originated from the orbital interactions of the Kagome lattices, while the Dirac bands are related to the carbon zigzag chains. A tight-binding model is used to explain the various band structures in different CKLs. The coexistence of flat and Dirac bands around the Fermi level implies that CKL structures maybe can serve as superconductors. In addition, electronic properties of the thinnest CKL slabs, only consisting of benzene rings, are studied. Flat bands are found in the band spectra of the two-dimensional structures, and split into spin-up and spin-down bands because of strong correlated effect in the case of hole doping.