Through a Lattice Darkly -- Shedding Light on Electron-Phonon Coupling in the High T$_c$ Cuprates

TL;DR

This review explores how electron-phonon interactions influence high-temperature cuprate superconductors using ARPES, isotope substitution, IXS, and strain experiments to understand their complex phase diagram.

Contribution

It provides a comprehensive analysis of electron-phonon coupling effects in cuprates through advanced spectroscopic techniques and recent experimental approaches.

Findings

Identification of the ubiquitous nodal kink in cuprates

Isotope substitution reveals the role of phonons in electron dynamics

Strain experiments suggest lattice effects influence superconductivity

Abstract

With its central role in conventional BCS superconductivity, electron-phonon coupling has appeared to play a more subtle role in the phase diagram of the high temperature superconducting cuprates. The added complexity of the cuprates with potentially numerous competing phases including charge, spin, orbital, and lattice ordering, makes teasing out any unique phenomena challenging. In this review, we present our work using angle resolved photoemission spectroscopy (ARPES) to explore the role of the lattice and its effect on the valence band electronic structure in the cuprates. We provide an introduction to the ARPES technique and its unique ability to the probe the effect of bosonic renormalization (or "kink") on the near-E$_F$ band structure. Our survey begins with the establishment of the ubiquitous nodal cuprate kink leading to the way isotope substitution has shed a critical new perspective on the role and strength of electron-phonon coupling. We continue with recently published work on the connection between the phonon dispersion as seen with inelastic x-ray scattering (IXS) and the location of the kink as observed by ARPES near the nodal point. Finally, we present very recent and ongoing ARPES work examining how induced strain through chemical pressure provides a potentially promising avenue for understanding the broader role of the lattice to the superconducting phase and larger cuprate phase diagram.