Spinon-Holon binding in $t-J$ model

TL;DR

This paper explores how spinon-holon binding in the $t-J$ model leads to a pseudo-gap state with a segmented Fermi surface and describes the formation of a d-wave superconducting gap that merges with the pseudo-gap at low temperatures.

Contribution

It introduces a phenomenological model showing that spinon-holon binding results in a pseudo-gap phase with a segmented Fermi surface and a superconducting state with a d-wave gap merging with the pseudo-gap.

Findings

Pseudo-gap normal state with segmented Fermi surface

Superconducting state formed by a d-wave gap on the segmented Fermi surface

Quasi-particle coupling to electromagnetic field depends on spinon-holon binding strength

Abstract

Using a phenomenological model, we discuss the consequences of spinon-holon binding in the U(1) slave-boson approach to $t-J$ model. Within a small $x$ ($x=$ hole concentration) expansion, we show that spinon-holon binding produces a pseudo-gap normal state with a segmented Fermi surface and the superconducting state is formed by opening an "additional" d-wave gap on the segmented Fermi surface. The d-wave gap merge with the pseudo-gap smoothly as temperature $T\to0$. The quasi-particles in the superconducting state are coupled to external electromagnetic field with a coupling constant of order $x^{\gamma}$ where $0\leq\gamma\leq1/2$, depending on the strength of the effective spinon-holon binding potential.