Dimensionally mixed coupled collective modes

TL;DR

This paper develops a diagrammatic many-body theory for coupled collective modes in multi-dimensional electron systems, revealing mixed plasmon modes with distinct characteristics in 2D-3D systems and extending to other dimensional combinations.

Contribution

It introduces a formalism for analyzing coupled collective modes across different dimensions, applicable to various dimensional combinations in electron systems.

Findings

Identified two mixed plasmon modes in 2D-3D systems, one 3D-like and one acoustic.

Modes are strongly coupled at larger wave vectors.

Formalism is general and applicable to other dimensional combinations.

Abstract

We develop the diagrammatic formulation of the many-body theory for the coupled collective modes in interacting electron systems of different dimensions. The formalism is then applied in detail to a two-dimensional system coupled to a three-dimensional electron gas. We find two dimensionally-mixed plasmon modes which in the long wavelength limit are respectively 3D-like and acoustic in nature, but are strongly coupled at larger wave vectors. The same formalism can be applied to any dimensional combinations, and we also present the results for 1D-2D and 1D-3D coupled systems.