The fate of orbitons coupled to phonons

TL;DR

This paper investigates how coupling between orbitons and phonons in one-dimensional systems affects their spectral properties, revealing band narrowing, continuum dominance, and observable anti-bound states through continuous unitary transformations.

Contribution

It introduces a detailed analysis of orbiton-phonon interactions in 1D using CUTs, highlighting new spectral features and bound states.

Findings

Orbiton band width is significantly reduced at intermediate coupling.

Spectral density is dominated by an orbiton-phonon continuum.

Sharp features and anti-bound states are observable within the continuum.

Abstract

The key feature of an orbital wave or orbiton is a significant dispersion, which arises from exchange interactions between orbitals on distinct sites. We study the effect of a coupling between orbitons and phonons in one dimension using continuous unitary transformations (CUTs). Already for intermediate values of the coupling, the orbiton band width is strongly reduced and the spectral density is dominated by an orbiton-phonon continuum. However, we find sharp features within the continuum and an orbiton-phonon anti-bound state above. Both show a significant dispersion and should be observable experimentally.