Theory of Quasi-Particles in the Underdoped High Tc Superconducting State

TL;DR

This paper develops a microscopic SU(2) slave-boson theory explaining how pseudogap features evolve into a d-wave superconducting gap in underdoped cuprates, linking normal state properties to BCS-like quasiparticles.

Contribution

It introduces a microscopic SU(2) slave-boson model that describes the evolution of pseudogap and Fermi surface segments into a d-wave superconducting gap.

Findings

Pseudogap and Fermi surface segments develop into a d-wave gap in the superconducting state.

Low-lying quasiparticles resemble those in BCS theory despite low superfluid density.

The theory underpins earlier phenomenological models of underdoped cuprates.

Abstract

The microscopic theory of superconducting (SC) state in the SU(2) slave-boson model is developed. We show how the pseudogap and Fermi surface (FS) segments in the normal state develop into a d-wave gap in the superconducting state. Even though the superfluid density is of order x (the doping concentration), the physical properties of the low lying quasiparticles are found to resemble those in BCS theory. Thus the microscopic theory lay the foundation for our earlier phenomenological discussion of the unusual SC properties in the underdoped cuprates.