Correlation effects in the iron pnictides

Abstract

One of the central questions about the iron pnictides concerns the extent to which their electrons are strongly correlated. Here we address this issue through the phenomenology of the charge transport and dynamics, single-electron excitation spectrum, and magnetic ordering and dynamics. We outline the evidence that the parent compounds, while metallic, have electron interactions that are sufficiently strong to produce incipient Mott physics. In other words, in terms of the strength of electron correlations compared to the kinetic energy, the iron pnictides are closer to intermediately-coupled systems lying at the boundary between itinerancy and localization, such as V2O3 or Se-doped NiS2, rather than to simple antiferromagnetic metals like Cr. This level of electronic correlations produces a new small parameter for controlled theoretical analyses, namely the fraction of the single-electron spectral weight that lies in the coherent part of the excitation spectrum. Using this expansion parameter, we construct the effective low-energy Hamiltonian and discuss its implications for the magnetic order and magnetic quantum criticality. Finally, this approach sharpens the notion of magnetic frustration for such a metallic system, and brings about a multiband matrix t-J1-J2 model for the carrier-doped iron pnictides.

14 pages, 2 figures, discussions on several points expanded, published in the Focus Issue on Iron-Based Superconductors

References in corpus (20)

• Magnetic Order versus superconductivity in the Iron-based layered La(O1-xFx)FeAs systems
• Unconventional pairing originating from disconnected Fermi surfaces in superconducting LaFeAsO${}_{1-x}$F${}_x$}
• LaFeAsO${}_{1-x}$F${}_x$: A low carrier density superconductor near itinerant magnetism
• Magnetic order in BaFe2As2, the parent compound of the FeAs based superconductors in a new structural family
• Structural and magnetic phase diagram of CeFeAsO1-xFx and its relationship to high-temperature superconductivity
• Superconductivity up to 37 K in (A1-xSrx)Fe2As2 with A=K and Cs
• Strong Correlations and Magnetic Frustration in the High Tc Iron Pnictides
• Competing Orders and Spin-Density-Wave Instability in La(O${}_{1-x}$F${}_x$)FeAs
• Origin of the ~150 K Anomaly in LaOFeAs; Competing Antiferromagnetic Superexchange Interactions, Frustration, and Structural Phase Transition
• Coexistence of the spin-density-wave and superconductivity in the (Ba,K)Fe2As2
• Electronic structure of the iron-based superconductor LaOFeP
• Proximity of antiferromagnetism and superconductivity in LaO${}_{1-x}$F${}_x$FeAs: effective Hamiltonian from ab initio studies
• Antiferromagnetic superexchange interactions in LaOFeAs
• Fermi surface of superconducting LaFePO determined by quantum oscillations
• Iron pnictides as a new setting for quantum criticality
• Transport and anisotropy in single-crystalline SrFe${}_2$As${}_2$ and $A_{0.6}$K${}_{0.4}$Fe${}_2$As${}_2$ ($A$ = Sr, Ba) superconductors
• Quantum oscillations in the parent magnetic phase of an iron arsenide high temperature superconductor
• Structure and Magnetic Order in the NdFeAs(O,F) Superconductor System
• Strong coupling between magnetic and structural order parameters in SrFe2As2
• High energy spin excitations in BaFe2As2