Role of Hund's coupling in stabilization of the (0,pi) ordered SDW state within the minimal two-band model for iron pnictides

TL;DR

This study explores how Hund's coupling influences the stability of the (0,pi) SDW state in a minimal two-band model for iron pnictides, revealing its role in stabilizing magnetic order across doping regimes.

Contribution

It demonstrates that Hund's coupling significantly stabilizes the (0,pi) SDW state by generating ferromagnetic interactions, extending understanding of magnetic stability in iron pnictides.

Findings

Hund's coupling stabilizes the SDW state in two doping regimes.

Spin wave energies match previous one-band Hubbard model results.

Results agree with inelastic neutron scattering experiments.

Abstract

Spin wave excitations and stability of the (0,pi) ordered SDW state are investigated within the minimal two-band model for iron pnictides including a Hund's coupling term. The SDW state is shown to be stable in two distinct doping regimes --- finite hole doping in the lower SDW band for small second neighbour hoppings, and small electron doping in the upper SDW band for comparable first and second neighbour hoppings. In both cases, Hund's coupling strongly stabilizes the SDW state due to generation of additional ferromagnetic spin couplings involving the inter-orbital part of the particle-hole propagator. Spin wave energies for the two-band model are very similar to the one-band t-t' Hubbard model results obtained earlier, and are in agreement with inelastic neutron scattering studies of iron pnictides.