ARPES studies of cuprate Fermiology: superconductivity, pseudogap, and quasiparticle dynamics

TL;DR

This paper uses ARPES to explore the complex relationship between superconductivity, the pseudogap, and quasiparticle behavior in cuprate high-temperature superconductors, revealing distinct states and momentum-dependent phenomena.

Contribution

It provides new insights into the coexistence of pseudogap and superconducting gaps and their different behaviors across momentum space in cuprates.

Findings

Pseudogap and superconducting gap are distinct and coexist below T_c.

Different regions in momentum space show different temperature and doping behaviors.

Presence of multiple 'kinks' in dispersion related to electron-boson coupling.

Abstract

We present angle-resolved photoemission spectroscopy (ARPES) studies of the cuprate high-temperature superconductors which elucidate the relation between superconductivity and the pseudogap and highlight low-energy quasiparticle dynamics in the superconducting state. Our experiments suggest that the pseudogap and superconducting gap represent distinct states, which coexist below T$_c$. Studies on Bi-2212 demonstrate that the near-nodal and near-antinodal regions behave differently as a function of temperature and doping, implying that different orders dominate in different momentum-space regions. However, the ubiquity of sharp quasiparticles all around the Fermi surface in Bi-2212 indicates that superconductivity extends into the momentum-space region dominated by the pseudogap, revealing subtlety in this dichotomy. In Bi-2201, the temperature dependence of antinodal spectra reveals particle-hole asymmetry and anomalous spectral broadening, which may constrain the explanation for the pseudogap. Recognizing that electron-boson coupling is an important aspect of cuprate physics, we close with a discussion of the multiple 'kinks' in the nodal dispersion. Understanding these may be important to establishing which excitations are important to superconductivity.