Unconventional Superconducting Symmetry in a Checkerboard Antiferromagnet

TL;DR

This study investigates the pairing symmetries in a frustrated extended Hubbard model on a checkerboard lattice, revealing a transition from d-wave to s-wave and mixed symmetries as frustration increases, using renormalized mean field theory.

Contribution

It introduces a comprehensive analysis of superconducting symmetries in a frustrated lattice model using Gutzwiller projected states and renormalized mean field theory, highlighting symmetry transitions with frustration.

Findings

At small t'/t, d_{x^2-y^2}-wave pairing dominates.

At large t'/t, the ground state exhibits extended s-wave symmetry.

Intermediate t'/t values show d+id or d+is wave states with broken time-reversal symmetry.

Abstract

We use a renormalized mean field theory to study the Gutzwiller projected BCS states of the extended Hubbard model in the large $U$ limit, or the $t$-$t'$-$J$-$J'$ model on a two-dimensional checkerboard lattice. At small $t'/t$, the frustration due to the diagonal terms of $t'$ and $J'$ does not alter the $d_{x^2-y^2}$-wave pairing symmetry, and the negative (positive) $t'/t$ enhances (suppresses) the pairing order parameter. At large $t'/t$, the ground state has an extended s-wave symmetry. At the intermediate $t'/t$, the ground state is $d+id$ or $d+is$-wave with time reversal symmetry broken.