Orbital-selective superconductivity, gap anisotropy and spin resonance excitations in a multiorbital t-J1-J2 model for iron pnictides

TL;DR

This study investigates how orbital-dependent interactions influence superconducting gap anisotropy and spin resonance features in a multiorbital model for iron pnictides, providing insights into experimental observations.

Contribution

It introduces a detailed five-orbital t-J1-J2 model that captures orbital selectivity effects on superconductivity and spin excitations in iron pnictides, highlighting the impact of magnetic frustration.

Findings

Superconducting gap anisotropy varies with J1-J2 magnetic frustration.

Spin resonance peak can split due to orbital-dependent gap anisotropy.

Resonance width is affected by the orbital character of the superconducting gap.

Abstract

We study the orbital-dependent superconducting pairing in a five-orbital t-J1-J2 model for iron pnictides. Depending on the orbital selectivity of electron correlations and the orbital characters along the Fermi surface, the superconducting gap in an A_{1g} pairing state may exhibit anisotropy. This anisotropy varies with the degree of J1-J2 magnetic frustration. We have also calculated the dynamical spin susceptibility in the superconducting state. The frequency dependence of the susceptibility at the antiferromagnetic wavevector (\pi,0) shows a resonance, whose width is enhanced by the orbital dependence of the superconducting gap; when the latter is sufficiently strong, the resonance peak may be split into two. We discuss the implications of our results on the recent angle-resolved photoemission and neutron-scattering measurements in several superconducting iron pnictides.