Optical conductivity of the $t_{2g}$ two-dimensional electron gas

TL;DR

This paper analyzes the optical conductivity of a $t_{2g}$ two-dimensional electron gas in perovskite oxides, revealing polarization-dependent features that can shed light on lattice and interaction effects in quantum confined systems.

Contribution

It provides a detailed theoretical analysis of the optical conductivity in $t_{2g}$ 2DEGs, highlighting polarization-dependent behaviors and potential for probing complex interactions.

Findings

In-plane polarization shows Drude-like conductivity from subband Fermi surfaces.

Perpendicular polarization exhibits strong intersubband features.

Study suggests optical measurements can reveal lattice distortions and electron interactions.

Abstract

Motivated by recent interest in perovskite surfaces and heterostructures, we present an analysis of the Kubo conductivity of a two-dimensional electron gas (2DEG) formed in the $t_{2g}$ bands of an oxide with perovskite structure. We find that when the electric field is polarized in the plane of the 2DEG, the optical conductivity is dominated by nearly independent Drude contributions from two-dimensional subband Fermi surfaces, whereas for perpendicular-to-plane polarization it has strong intersubband features. Our analysis suggests that perpendicular-to-plane optical conductivity studies may help advance understanding of the interplay between lattice distortions and electron-electron interactions in complex oxide 2DEG quantum confinement physics.