What the resonance peak does

TL;DR

This study uses high-resolution photoemission to distinguish bilayer splitting from intrinsic effects in cuprate superconductors, revealing doping-dependent intrinsic effects linked to the resonance mode.

Contribution

It provides direct evidence of intrinsic electronic effects below Tc in underdoped samples, supporting models involving strong coupling with neutron resonance modes.

Findings

Intrinsic effects are present only below Tc in underdoped samples.

Intrinsic effects weaken with increased doping.

Results support models linking electronic excitations to neutron resonance modes.

Abstract

High-resolution angle-resolved photoemission with variable excitation energies is used to disentangle bilayer splitting effects and intrinsic (self-energy) effects in the electronic spectral function near the ($\pi$,0)-point of differently doped (Pb,Bi)$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$. In contrast to overdoped samples, where intrinsic effects at the ($\pi$,0)point are virtually absent, we find in underdoped samples \textit{intrinsic} effects in the superconducting-state ($\pi$,0) spectra of the antibonding band. This intrinsic effect is present only below the critical temperature and weakens considerably with doping. Our results give strong support for models which involve a strong coupling of electronic excitations with the resonance mode seen in inelastic neutron scattering experiments.