Superconducting Properties of Two-Orbital t-t'-J-J' Models

TL;DR

This paper investigates the superconducting properties of two-orbital t-t'-J-J' models to explain experimental observations in iron-based superconductors, suggesting an anisotropic nodeless s-wave pairing symmetry driven by band structure and Fermi surface topology.

Contribution

It provides a comprehensive theoretical analysis of phase diagrams, Fermi surfaces, ARPES quasiparticle features, and spin relaxation, clarifying the pairing symmetry in iron pnictides.

Findings

Most properties of iron-based superconductors are qualitatively explained.

The pairing symmetry is identified as anisotropic nodeless s-wave.

Results highlight the role of band structure and Fermi surface topology.

Abstract

Motivated by the recent contradiction of the superconducting pairing symmetry in the angle-resolved photoemission spectra (ARPES) and the nuclear magnetic resonance (NMR) data in the FeAs superconductors, we present the theoretical results on the phase diagram, the temperature dependent Fermi surfaces in normal state, the ARPES character of quasiparticles and the spin-lattice relaxation 1/T$_{1}$ of the two-orbital t-t$^{'}$-J-J$^{'}$ models. Our results show that most of the properties observed in iron-based superconductors could be comprehensively understood in the present scenario qualitatively, indicating that the pairing symmetry of the ironpnictides is anisotropic nodeless s-wave, mainly originating from the band structures and the Fermi surface topology.