Spin excitations in the excitonic spin-density-wave state of the iron pnictides

Abstract

Motivated by the iron pnictides, we examine the spin excitations in an itinerant antiferromagnet where a spin-density wave (SDW) originates from an excitonic instability of nested electron-like and hole-like Fermi pockets. Using the random phase approximation (RPA), we derive the Dyson equation for the transverse susceptibility in the excitonic SDW state. The Dyson equation is solved for two different two-band models, describing an antiferromagnetic insulator and metal, respectively. We determine the collective spin-wave dispersions and also consider the single-particle continua. The results for the excitonic models are compared with each other and also contrasted with the well-known SDW state of the Hubbard model. Despite the qualitatively different SDW states in the two excitonic models, their magnetic response shows many similarities. We conclude with a discussion of the relevance of the excitonic SDW scenario to the iron pnictides.

arXiv comment17 pages, 18 figures, v2: expanded discussion of spin-wave velocity, added references

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• Excitonic condensation in systems of strongly correlated electrons
• Theory of itinerant magnetic excitations in the SDW phase of iron-based superconductors
• Spin and Charge Dynamics Ruled by Antiferromagnetic Order in Iron Pnictides
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• Realizing intrinsic excitonic insulator by decoupling exciton binding energy from the minimum band gap
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• Quasiparticle interference in iron-based superconductors
• Multiorbital Spin Susceptibility in a Magnetically Ordered State - Orbital versus Excitonic Spin Density Wave Scenario
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• Magnetic order in orbital models of the iron pnictides
• Spin Waves in Detwinned BaFe${}_2$As${}_2$
• A New Era of Excitonic Insulators
• Effect of intraband Coulomb repulsion on the excitonic spin-density wave
• Spin excitations in the nematic phase and the metallic stripe spin-density wave phase of iron pnictides
• LDA+DMFT approach to ordering phenomena and the structural stability of correlated materials
• Spin-Density-Wave Gap with Dirac Nodes and Two-Magnon Raman Scattering in BaFe2As2
• Impact of Dynamic Orbital Correlations on Magnetic Excitations in the Normal State of Iron-Based Superconductors
• Magnetic resonance from the interplay of frustration and superconductivity
• Electric and magnetic multipoles and bond orders in excitonic insulators
• Superconducting pairing in the spin-density-wave phase of iron pnictides
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• Double magnetic resonance and spin anisotropy in Fe-based superconductors due to static and fluctuating antiferromagnetic orders
• Role of Hund's coupling in stabilization of the (0,pi) ordered SDW state within the minimal two-band model for iron pnictides
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• Spin resonance in AFe2Se2 with s-wave pairing symmetry
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• Distortional weak-coupling instability of Bogoliubov Fermi surfaces
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• Excitonic Insulator State of the Extended Falicov-Kimball Model in the Cluster Dynamical Impurity Approximation
• Excitonic Instabilities and Insulating States in Bilayer Graphene
• Competing phases in a model of Pr-based cobaltites
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• Excitonic enhancement of cavity-mediated interactions in a two-band Hubbard model
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• Electron-hole pairing of Fermi-arc surface states in a Weyl-semimetal bilayer
• Spin-wave excitations in the SDW state of doped iron pnictides