Prediction of above $20$ K superconductivity of blue phosphorus bilayer with metal intercalations

TL;DR

This study predicts that intercalating alkali and alkaline earth metals into blue phosphorus bilayers induces superconductivity with transition temperatures above 14K, making it a promising 2D superconductor.

Contribution

It identifies favorable metal intercalations and stacking configurations that transform blue phosphorus bilayer into a high-temperature superconductor via first-principles calculations.

Findings

Superconducting transition temperatures of 20.4K, 20.1K, and 14.4K for Li, Na, and Mg intercalations.

Blue phosphorus bilayer transitions from semiconductor to metal upon metal intercalation.

Intercalation enhances electron-phonon coupling, inducing superconductivity.

Abstract

First-principles calculations predicted monolayer blue phosphorus to be an alternative two-dimensional allotrope of phosphorus, like the recently discovered monolayer black phosphorus. Due to its unique crystalline and electronic structure, blue phosphorus may be a promising candidate as a BCS-superconductor after proper intercalation. In this study, using first-principles calculations, the favorable intercalation sites for some alkali metals and alkaline earths have been identified for Blue-P bilayer and the stacking configuration of bilayer is changed. Then the blue phosphorus bilayer transforms from a semiconductor to a metal due to the charge transfer from metal to phosphorus. Own to the strong electron-phonon coupling, isotropic superconducting state is induced and the calculated transition temperatures are $20.4$, $20.1$, and $14.4$K for Li-, Na-, and Mg-intercaltion, respectively, which is superior to other predicted or experimentally observed two-dimensional BCS-superconductors.