Screening, Kohn anomaly, Friedel oscillation, and RKKY interaction in bilayer graphene

TL;DR

This paper investigates the screening properties, Kohn anomaly, Friedel oscillation, and RKKY interaction in bilayer graphene, revealing significant differences from single-layer graphene and 2DEG, with implications for electronic behavior.

Contribution

It provides a detailed comparison of screening and related phenomena in bilayer graphene versus single-layer graphene and 2DEG, highlighting unique features of BLG.

Findings

Kohn anomaly is strongly enhanced in BLG.

Friedel oscillation and RKKY interaction differ qualitatively in BLG.

Screening function behavior varies between intrinsic and extrinsic regimes.

Abstract

We calculate the screening function in bilayer graphene (BLG) both in the intrinsic (undoped) and the extrinsic (doped) regime within random phase approximation, comparing our results with the corresponding single layer graphene (SLG) and the regular two dimensional electron gas (2DEG). We find that the Kohn anomaly is strongly enhanced in BLG. We also discuss the Friedel oscillation and the RKKY interaction, which are associated with the non-analytic behavior of the screening function at $q=2k_F$. We find that the Kohn anomaly, the Friedel oscillation, and the RKKY interaction are all qualitatively different in the BLG compared with the SLG and the 2DEG.