# Interlayer decoupling in twisted bilayers of $\beta$-phosphorus and arsenic: a computational study

## TL;DR

This computational study explores how twisting bilayers of blue phosphorus and grey arsenene creates interlayer decoupling, significantly altering their electronic and magnetic properties, including increased bandgap and induced ferromagnetism.

## Contribution

It demonstrates that twisting these bilayers reduces interlayer coupling and enhances magnetic and electronic tunability, revealing new potential for 2D material engineering.

## Key findings

- Interlayer decoupling increases with twist angle.
- Bandgap enlarges by up to 50% in twisted bilayers.
- Ferromagnetism is induced by hole doping in Moiré superlattices.

## Abstract

We investigate magnetism and band structure engineering in Moir\'e superlattice of blue phosphorus ($\beta$-P) and grey arsenene ($\beta$-As) bilayers, using \textit{ab initio} calculations. The electronic states near the valence and conduction band edges have significant $p_z$ character in both the bilayers. Thus, twisting the layers significantly reduce the interlayer orbital overlap, leading to a decrease in the binding energy (up to $\sim33\%$) and an increase in interlayer distance (up to $\sim10\%$), compared to the most stable AA-stacking. This interlayer decoupling also results in a notable increase (up to $\sim$25-50\%) of the bandgap of twisted bilayers, with the valance band edge becoming relatively flat with van-Hove singularities in the density of states. Thus, hole doping induces a Stoner instability, leading to ferromagnetic ground state, which is more robust in Moir\'e superlattices, than that of AA-stacked $\beta$-P and $\beta$-As.