The role of orbital order in the stabilization of the $(\pi ,0)$ ordered magnetic state in a minimal two-band model for iron pnictides

Abstract

Spin wave excitations and stability of the ($\pi ,0$) ordered magnetic state are investigated in a minimal two-band itinerant-electron model for iron pnictides. Presence of hopping anisotropy generates a strong ferro-orbital order in the $d_{xz}$ and $d_{yz}$ Fe orbitals. The orbital order sign is as observed in experiments. The induced ferro-orbital order strongly enhances the spin wave energy scale and stabilizes the magnetic state by optimizing the strength of the emergent AF and F spin couplings through optimal band fillings in the two orbitals. The calculated spin-wave dispersion is in quantitative agreement with neutron scattering measurements. Finite inter-orbital Hund's coupling is shown to further enhance the spin wave energies state by coupling the two magnetic sub-systems. A more realistic two-band model with less hopping anisotropy is also considered which yields not only the circular hole pockets, also correct ferro-orbital order and emergent F spin coupling.

5 pages, 7 figures

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Cited by in corpus (3)

• Electronic structure, spin excitations, and orbital ordering in a three-orbital model for iron pnictides
• Magneto-orbital coupling in iron pnictides
• Orbital-lattice coupling and orbital ordering instability in iron pnictides