Bilayer Kagome Borophene with Multiple van Hove Singularities

TL;DR

This paper proposes a new bilayer Kagome borophene with multiple van Hove singularities, predicted to be stable and exhibiting unique electronic properties, providing a platform for studying quantum correlation phenomena.

Contribution

The study introduces a novel bilayer Kagome borophene with multiple van Hove singularities, predicted through first-principles calculations to be stable and exhibit unique electronic features.

Findings

Presence of both conventional and high-order van Hove singularities near the Fermi level.

High-order singularity intersects a Dirac-like cone with high Fermi velocity.

Interaction between Kagome layers is key to high-order singularities.

Abstract

The appearance of van Hove singularities near the Fermi level leads to prominent phenomena, including superconductivity, charge density wave, and ferromagnetism. Here a bilayer Kagome lattice with multiple van Hove singularities is designed and a novel borophene with such lattice (BK-borophene) is proposed by the first-principles calculations. BK-borophene, which is formed via three-center two-electron (3c-2e) sigma-type bonds, is predicted to be energetically, dynamically, thermodynamically, and mechanically stable. The electronic structure hosts both conventional and high-order van Hove singularities in one band. The conventional van Hove singularity resulting from the horse saddle is 0.065 eV lower than the Fermi level, while the high-order one resulting from the monkey saddle is 0.385 eV below the Fermi level. Both the singularities lead to the divergence of electronic density of states. Besides, the high-order singularity is just intersected to a Dirac-like cone, where the Fermi velocity can reach 1340000 m/s. The interaction between the two Kagome lattices is critical for the appearance of high-order van Hove singularities. The novel bilayer Kagome borophene with rich and intriguing electronic structure offers an unprecedented platform for studying correlation phenomena in quantum material systems and beyond.