Electronic Spectra and Their Relation to the (pi,pi) Collective Mode in High-Tc Superconductors

TL;DR

This paper investigates the electronic spectra of high-Tc superconductors, revealing how the 'hump' feature relates to the superconducting gap, collective modes, and doping levels, providing insights into the pseudogap phase and electron interactions.

Contribution

It demonstrates the connection between photoemission spectra, the (pi,pi) collective mode, and doping dependence, offering a unified understanding of spectral features in high-Tc superconductors.

Findings

The 'hump' scales with the superconducting gap and persists above Tc.

Dispersion of the hump reflects the (pi,pi) wavevector as doping decreases.

Doping dependence of neutron resonance matches spectral observations.

Abstract

Photoemission spectra of Bi2Sr2CaCu2O8 reveal that the high energy feature near (pi,0), the "hump", scales with the superconducting gap and persists above Tc in the pseudogap phase. As the doping decreases, the dispersion of the hump increasingly reflects the wavevector (pi,pi) characteristic of the undoped insulator, despite the presence of a large Fermi surface. This can be understood from the interaction of the electrons with a collective mode, supported by our observation that the doping dependence of the resonance observed by neutron scattering is the same as that inferred from our data.