Flat and Correlated Plasmon Bands in Graphene/${\alpha}$-RuCl${_3}$ Heterostructures

TL;DR

This paper develops a microscopic theory for plasmon excitations in graphene/${\alpha}$-RuCl${_3}$ heterostructures, revealing novel correlated plasmon bands due to flat bands and interactions, consistent with experimental data and with implications for other flat band systems.

Contribution

It introduces a new theoretical framework combining Kondo-Kitaev models to explain plasmon behavior in heterostructures with flat bands and fractionalized fermions.

Findings

Discovery of flat and correlated plasmon bands in heterostructures.

Prediction of novel plasmon branches beyond long-wavelength limit.

Consistency with existing experimental data on graphene/${\alpha}$-RuCl${_3}$.

Abstract

We develop a microscopic theory for plasmon excitations of graphene/${\alpha}$-RuCl${_3}$ heterostructures. Within a Kondo-Kitaev model with various interactions, a heavy Fermi liquid hosting flat bands emerges in which the itinerant electrons of graphene effectively hybridize with the fractionalized fermions of the Kitaev quantum spin liquid. We find novel correlated plasmon bands induced by the interplay of flat bands and interactions and argue that our theory is consistent with the available experimental data on graphene/${\alpha}$-RuCl${_3}$ heterostructures. We predict novel plasmon branches beyond the long-wavelength limit and discuss the implications for probing correlation phenomena in other flat band systems.