Realizing high-temperature superconductivity in borophene with Dirac states assembled by kagome and honeycomb boron layers

Abstract

Boron's unique electron deficiency allows for the formation of various borophene polymorphs that have the potential for superconductivity. Herein, we have introduced a new route to realize high superconductivity in borophene through kagome and honeycomb boron layers assembly. We have designed a tri-layer borophene, named hP8-B, consisting of two AA-stacked kagome layers with a honeycomb layer serving as the interlayer. hP8-B possesses high superconductivity with an estimated Tc of 35.6 K, holding the highest value in any elemental 2D materials. The high Tc is mainly contributed by the strong coupling of σ-bonding electrons of the kagome layers and in-plane vibrational modes, which differs from that in other superconductive borophene polymorphs. Electronic band structure calculations showcase the existence of a Dirac cone near the Fermi level, indicating that hP8-B may be a potential topological superconductor. The superconductivity of hP8-B can be enhanced to 46.4 K under a biaxial tensile strain of 3% and doping density of 0.0375 holes per atom, due to the softening of the in-plane vibrational modes.