Frequency Shifts and Linewidth Changes of Infrared-Active Phonons in Double-Layered High-Temperature Superconductors

TL;DR

This paper models how infrared-active phonons in double-layer high-temperature superconductors shift in frequency and linewidth due to electron-phonon interactions, successfully matching experimental observations.

Contribution

It introduces a shell model for phonons coupled to a double-layer electronic structure, providing a theoretical explanation for observed phonon behavior in YBaCuO.

Findings

Accurately describes experimental phonon shifts and linewidth changes in YBaCuO.

Explains differences in phonon behavior between normal and superconducting states.

Abstract

We calculate frequency shifts and changes in linewidths of infrared-active phonons within a shell model for the bare phononic system coupled to an electronic double-layer structure with inter-layer charge transfer. The theoretical concept is applied to YBaCuO yielding a good description of experimental results in the normal state as well as at the transition to the superconducting state.