Collective Modes and the Superconducting State Spectral Function of Bi2212

TL;DR

This paper models the spectral function of Bi2212 in the superconducting state, explaining the evolution of photoemission spectra below Tc through electron interactions with a collective mode.

Contribution

It introduces a simple model of electron interactions with a collective mode that appears only below Tc, capturing the spectral changes observed in experiments.

Findings

The model reproduces the transition from broad peaks to sharp low energy peaks below Tc.

The low energy peak persists over a significant momentum range.

The collective mode is only present in the superconducting state.

Abstract

Photoemission spectra of the high temperature superconductor Bi2212 near (pi,0) show a dramatic change when cooling below Tc: the broad peak in the normal state turns into a sharp low energy peak followed by a higher binding energy hump. Recent experiments find that this low energy peak persists over a significant range in momentum space. We show in this paper that these data are well described by a simple model of electrons interacting with a collective mode which appears only below Tc.