Broadening and sharpening of the Drude peak through antiferromagnetic fluctuations

TL;DR

This paper investigates how antiferromagnetic fluctuations, modeled via RPA ladder diagrams, influence the optical conductivity in correlated electron systems, revealing temperature-dependent broadening or sharpening of the Drude peak.

Contribution

It introduces a semi-analytical RPA-based approach to study {\pi}-ton vertex corrections to optical conductivity, validating its qualitative accuracy in the Hubbard model.

Findings

Vertex corrections can broaden or sharpen the Drude peak depending on temperature.

RPA qualitatively reproduces {\pi}-ton} vertex corrections in the Hubbard model.

The study provides insights into the role of antiferromagnetic fluctuations in optical responses.

Abstract

Antiferromagnetic or charge density wave fluctuations couple with light through the recently discovered {\pi}-ton contribution to the optical conductivity, and quite generically constitute the dominant vertex corrections in low-dimensional correlated electron systems. Here we study the arguably simplest version of these $\pi$-tons based on the semi-analytical random phase approximation (RPA) ladder in the transversal particle-hole channel. The vertex corrections to the optical conductivity are calculated directly for real frequencies. We validate that the RPA qualitatively reproduces the {\pi}-ton vertex corrections to the Drude peak in the Hubbard model. Depending on the temperature we find vertex corrections to broaden or sharpen the Drude peak.