Bilayer Kagome Borophene with Multiple van Hove Singularities

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 1.34 x 106 m s-1. 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. A bilayer Kagome lattice will lead to multiple van Hove singularities. BK-borophene is a novel 2D boron allotrope, which constructed from the bilayer Kagome lattice. Its electronic structure hosts both conventional and high-order van Hove singularities near the Fermi level, and the high-order singularity is just intersected to a Dirac-like cone.image

Automated summary

By using first-principles calculations, a bilayer Kagome lattice with multiple van Hove singularities is designed and a novel borophene (BK-borophene) with such lattice is proposed. The BK-borophene 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.