Role of spinon and spinon singlet pair excitations on phase transitions in $d-wave$ superconductors

TL;DR

This paper investigates how spinon and spin singlet pair excitations influence phase transitions in d-wave superconductors, revealing their role in vortex stabilization without changing the transition's universality class.

Contribution

It demonstrates that massless spinon and spin singlet pair excitations do not alter the XY universality class but induce an attractive vortex interaction, stabilizing vortex pairs in lightly doped high T_c samples.

Findings

Spinon and spin singlet pair excitations do not change the phase transition universality class.

These excitations induce an attractive potential between vortices.

Vortex-antivortex pairs are stabilized at low temperatures in lightly doped samples.

Abstract

We examine the roles of massless Dirac spinon and spin singlet pair excitations on the phase transition in $d-wave$ superconductors. Although the massless spinon excitations in the presence of the spin singlet pair excitations do not alter the nature of the phase transition at $T = 0$, that is, the XY universality class, they are seen to induce an additional attractive interaction potential between vortices, further stabilizing vortex-antivortex pairs at low temperature for lightly doped high $T_c$ samples.