Disentangling Electron-Boson Interactions on the Surface of a Familiar Ferromagnet

TL;DR

This study investigates and distinguishes electron-phonon and electron-magnon interactions on Ni(111) surface resonances, revealing their unique signatures and dependencies in energy and momentum.

Contribution

It provides a detailed analysis of how electron-boson interactions can be disentangled and characterized on a ferromagnetic surface, highlighting their different behaviors.

Findings

Electron-magnon interactions depend strongly on momentum and energy band position.

Electron-phonon interactions are relatively momentum- and symmetry-independent.

A significant electron-phonon coupling ($rac{1}{2}$) is identified on a spin majority band.

Abstract

We report energy renormalizations from electron-phonon and electron-magnon interactions in spin minority surface resonances on Ni(111). The different interactions are identified, disentangled, and quantified from the characteristic signatures they provide to the complex self-energy and the largely different binding energies at which they occur. The observed electron-magnon interactions exhibit a strong dependence on momentum and energy band position in the bulk Brillouin zone. In contrast, electron-phonon interactions from the same bands appear to be relatively momentum- and symmetry-independent. Additionally, a moderately strong ($\lambda>0.5$) electron-phonon interaction is distinguished from a near-parabolic spin majority band not crossing the Fermi level.