# Electromagnetic modes from Stoner enhancement

## TL;DR

This paper investigates how spin fluctuations and Stoner excitations influence electromagnetic modes in graphene, revealing a new TM mode in undoped graphene and providing insights into spin fluctuation effects on optical conductivity.

## Contribution

It provides a detailed analysis of Stoner excitation effects on electromagnetic modes in graphene, highlighting the emergence of a new TM mode in undoped graphene due to ladder diagram corrections.

## Key findings

- No effect on TE mode in doped graphene
- Emergence of a new undamped TM mode in undoped graphene
- Stoner excitations can be directly probed through electromagnetic response

## Abstract

Systems with substantial spin fluctuations, can internally dress the polarization function by ladder diagram of Stoner (spin-flip) excitations. This process can drastically modify the electromagnetic response. As a case study we provide detailed analysis of the corrections to the non-local optical conductivity of both doped and undoped graphene. While the resummation of ladder diagram of Stoner excitations does not affect the TE mode in doped graphene, it allows for a new undampled TM mode in undoped graphene. This is the sole effect of corrections arising from ladder diagrams and is dominated by Stoner excitations along the ladder rung which goes away by turning off the source of spin-flip interactions. This can be considered as a direct probe of the spin fluctuations.