Evidence for bosonic mode coupling in electron dynamics of LiFeAs superconductor

TL;DR

This study uses high-resolution laser ARPES to identify three energy scales in LiFeAs, providing evidence of electron coupling with bosonic modes, likely phonons, in both superconducting and normal states.

Contribution

First direct observation of multiple bosonic mode couplings in LiFeAs, confirming their role in electron dynamics of iron-based superconductors.

Findings

Identified three energy scales at ~20, ~34, and ~55 meV.

Confirmed electron coupling with phonon-like bosonic modes.

Provided evidence of mode coupling in both superconducting and normal states.

Abstract

Super-high resolution laser-based angle-resolved photoemission measurements are carried out on LiFeAs superconductor to investigate its electron dynamics. Three energy scales at $\sim$20 meV, $\sim$34 meV and $\sim$55 meV are revealed for the first time in the electron self-energy both in the superconducting state and normal state. The $\sim$20 meV and $\sim$34 meV scales can be attributed to the coupling of electrons with sharp bosonic modes which are most likely phonons. These observations provide definitive evidence on the existence of mode coupling in iron-based superconductors.