Normal State Spin Dynamics of Five-band Model for Iron-pnictides

TL;DR

This paper investigates the spin dynamics of iron-pnictide superconductors using an itinerant five-band model within RPA, successfully reproducing experimental neutron scattering and NMR results without localized spins.

Contribution

It introduces a comprehensive five-band itinerant model that explains spin dynamics and magnetic properties of iron-pnictides, challenging localized spin models.

Findings

Column-like response at (pi, 0) matches neutron scattering data

Temperature dependence of neutron scattering intensity is accurately reproduced

Itinerant model captures NMR 1/T_1T behavior

Abstract

Normal state spin dynamics of the recently discovered iron-pnictide superconductors is discussed by calculating spin structure factor S(q, omega) in an itinerant five-band model within RPA approximation. Due to the characteristic Fermi surface structure of iron-pnictide, column like response is found at (pi, 0) in extended Brillouin zone in the undoped case, which is consistent with the recent neutron scattering experiment. This indicates that the localized spin model is not necessary to explain the spin dynamics of this system. Furthermore, we show that the temperature dependence of inelastic neutron scattering intensity can be well reproduced in the itinerant model. We also study NMR 1/T_1T in the same footing calculation and show that the itinerant model can capture the magnetic property of iron-pnictide superconductors.