On the nature of superconductor pseudogaps

TL;DR

This paper explores the origin of pseudogaps in high-temperature cuprate superconductors, proposing a multiband model with interband pairing that explains pseudogaps as precursor excitations related to doping-dependent spectral changes.

Contribution

It introduces a multiband framework with interband pairing to explain pseudogaps as non-pairing excitations, linking their emergence to doping-driven spectral overlaps.

Findings

Pseudogaps arise from bands with the Fermi energy outside the pairing-active region.

Pseudogaps are precursors to superconducting gaps, not indicators of pairing strength.

The phase diagram features critical points determined by doping-induced spectral overlaps.

Abstract

The physical origin of cuprate high-temperature superconductor pseudogaps remains debatable. We point out that the indication of such excitation is hidden in the usual expression for the quasiparticle energy. It can be realized on a suitable multiband spectrum with an interband pairing channel. The band components bearing the chemical potential manifest superconducting gaps. A band with the Fermi energy outside creates a pseudogap type excitation. The latter does not characterize the pairing strength. On a doping-driven spectral arrangement the nature of low-energy excitations changes with doping. The pseudogap appears as a precursor of the corresponding superconducting gap on the doping scale. The corresponding critical points on the phase diagram are determined by the doping-driven overlap dynamics of the bare gapped electron spectrum.