Spin Density Wave and D-Wave Superconducting Order Parameter "Coexistence"

TL;DR

This paper investigates the coexistence of spin-density-wave antiferromagnetism and d-wave superconductivity, analyzing their interplay and effects on quasiparticle properties in a mean-field framework relevant to cuprate superconductors.

Contribution

It provides a numerical study of how weak antiferromagnetic order coexists with d-wave superconductivity and affects quasiparticle excitations and local density of states.

Findings

Antiferromagnetic order opens a small gap for nodal quasiparticles.

Coexistence leads to discernible quasiparticle peaks in the density of states.

Weak antiferromagnetism modifies the quasiparticle absorption spectrum.

Abstract

We study the properties of a spin-density-wave antiferromagnetic mean-field ground state with d-wave superconducting (DSC) correlations. This ground state always gains energy by Cooper pairing. It would fail to superconduct at half-filling due to the antiferromagnetic gap although its particle-like excitations would be Bogolyubov-BCS quasiparticles consisting of coherent mixtures of electrons and holes. More interesting and relevant to the superconducting cuprates is the case when antiferromagnetic order is turned on weakly on top of the superconductivity. This would correspond to the onset of antiferromagnetism at a critical doping. In such a case a small gap proportional to the weak antiferromagnetic gap opens up for nodal quasiparticles, and the quasiparticle peak would be discernible. We evaluate numerically the absorption by nodal quasiparticles and the local density of states for several ground states with antiferromagnetic and d-wave superconducting correlations.