X-ray edge singularity of bilayer graphene

TL;DR

This paper investigates the X-ray edge singularity in bilayer graphene, revealing unique behaviors influenced by interlayer coupling and bias, differing from monolayer graphene.

Contribution

It extends the path integral approach to bilayer graphene, demonstrating singularity presence at half-filling and analyzing bias-dependent effects.

Findings

Edge singularity exists at half-filling in bilayer graphene.

Singularity characteristics are governed by interlayer coupling.

Bias affects the singular behavior due to band structure changes.

Abstract

The X-ray edge singularity of bilayer graphene is studied by generalizing the path integral approach based on local action which was employed for monolayer graphene. In sharp contrast to the case of monolayer graphene, the bilayer graphene is found to exhibit the edge singularity even at half-filling and its characteristics are determined by interlayer coupling. At finite bias the singular behaviors sensitively depend on the relative magnitude of fermi energy and applied bias, which is due to the peculiar shape of energy band at finite bias.