Interlayer decoupling in twisted bilayers of β-phosphorus and arsenic: A computational study

Abstract

We investigate magnetism and band structure engineering in Moiré superlattice of blue phosphorus (β-P) and grey arsenene (β-As) bilayers, using ab initio calculations. The electronic states near the valence and conduction band edges have significant pz 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 ∼ 33%) and an increase in interlayer distance (up to ∼ 10%), compared to the most stable AA-stacking. This interlayer decoupling also results in a notable increase (up to ∼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 Moiré superlattices, than that of AA-stacked β-P and β-As. arXiv:1905.05951v1 [cond-mat.mtrl-sci] 15 May 2019 * bsomnath@iitk.

Interplay between structural deformations and flat band phenomenology in twisted bilayer antimonene

“…In this respect, the results are similar to those reported for the other pnictogens, phosphorous and arsenic, both beta-phase bilayers. 22,23 This is interesting since unconventional superconductivity 1 and insulating strongly correlated states 2 are ascribed to the existence of at bands below the Fermi level in twisted structures, but only for very small magic angles. The emergence of at bands in the relatively greater twist angles shown in Fig.…”

Ultra-flat bands at large twist angles in group-V twisted bilayer materials

“…[28][29][30] To date, the band structures of the β-P, β-As, and β-Sb twisted systems have also been explored by density functional theory (DFT) methods. [31][32][33][34] An et al found that the flat bandwidth of 10 meV in β-Sb appeared at 6.01 ○ . 34 Agnihotri et al studied the evolution of interlayer coupling in twisted bilayers of β-P and β-As, resulting in significant changes in the bandgap.…”

“…34 Agnihotri et al studied the evolution of interlayer coupling in twisted bilayers of β-P and β-As, resulting in significant changes in the bandgap. 31 However, due to limited computational resources, investigations have been limited to the small system with an angle of 3.89 ○ and 868 atoms. Larger systems with thousands of atoms remain largely unexplored.…”

“…We can find that a, r, and h are in good agreement with the previous study. 31,33,49,50 However, the interlayer distance differs by ∼6%, 33,[50][51][52] which can be sourced from the different methods used to treat vdW interaction. In this study, the DFT-D3 method with Becke Jonson damping is used, which is distinguished from the previous study.…”