Superconductivity and spin triplet collective mode in the t-J model close to antiferromagnetic instability

TL;DR

This paper explores the interplay between antiferromagnetic order, superconductivity, and triplet excitations in a modified t-J model near AF instability, revealing coexistence and emergent collective modes.

Contribution

It introduces a modified t-J model with additional parameters to control proximity to AF instability and analytically demonstrates coexistence of AF order and d-wave superconductivity.

Findings

Coexistence of long-range AF order and d-wave superconductivity.

Emergence of spin triplet collective mode below the superconducting gap near AF instability.

Analytical demonstration of superconducting gaps and spin wave renormalization.

Abstract

To investigate relations between long-range antiferromagnetic (AF) order, superconductivity and two particle triplet collective excitations we consider a modified two dimensional t-J model at doping close to half filling. The model includes additional hopping t'' and nearest sites Coulomb repulsion V. The additional parameters allow us to control closeness of the system to the AF instability. We demonstrate the possibility of co-existence of long-range AF order and d-g-wave superconductivity. In the phase with long-range AF order we find, analytically, superconducting gaps and spin wave renormalization. We demonstrate that at approaching the point of the AF instability the spin triplet collective excitation arises with energy below the superconducting gap.