Electronic correlations in the iron pnictides

Abstract

In correlated metals derived from Mott insulators, the motion of an electron is impeded by Coulomb repulsion due to other electrons. This phenomenon causes a substantial reduction in the electron's kinetic energy leading to remarkable experimental manifestations in optical spectroscopy. The high-Tc superconducting cuprates are perhaps the most studied examples of such correlated metals. The occurrence of high-Tc superconductivity in the iron pnictides puts a spotlight on the relevance of correlation effects in these materials. Here we present an infrared and optical study on single crystals of the iron pnictide superconductor LaFePO. We find clear evidence of electronic correlations in metallic LaFePO with the kinetic energy of the electrons reduced to half of that predicted by band theory of nearly free electrons. Hallmarks of strong electronic many-body effects reported here are important because the iron pnictides expose a new pathway towards a correlated electron state that does not explicitly involve the Mott transition.

10 pages

References in corpus (25)

• Magnetic Order versus superconductivity in the Iron-based layered La(O1-xFx)FeAs systems
• LaFeAsO${}_{1-x}$F${}_x$: A low carrier density superconductor near itinerant magnetism
• Kramers-Kronig constrained variational analysis of optical spectra
• Strong Correlations and Magnetic Frustration in the High Tc Iron Pnictides
• Is LaO${}_{1-x}$F${}_x$FeAs an electron-phonon superconductor ?
• Correlated electronic structure of LaOFeAs
• Electronic structure and magnetism in Ru based perovskites
• Electronic structure of the iron-based superconductor LaOFeP
• Band Structure and Transport Properties of CrO_2
• Origin of the spin density wave instability in AFe${}_2$As${}_2$ (A=Ba, Sr) as revealed by optical spectroscopy
• Fermi surface of superconducting LaFePO determined by quantum oscillations
• Correlated metallic state of vanadium dioxide
• Transfer of Spectral Weight in Spectroscopies of Correlated Electron Systems
• Transport, optical and electronic properties of the half metal CrO2
• Optical conductivity and the correlation strength of high temperature copper-oxide superconductors
• On the optical conductivity of Electron-Doped Cuprates I: Mott Physics
• Electronic structures of ternary iron arsenides AFe${}_2$As${}_2$ (A=Ba, Ca, or Sr)
• Optical spectroscopy of superconducting Ba{0.55}K{0.45}Fe2As2: evidence for strong coupling to low energy bosons
• Electromagnetic properties and electronic structure of iron-based layered superconductor LaOFeP
• Spectral evolution in (Ca,Sr)RuO_3 near the Mott-Hubbard transition
• MuSR studies of RE(O,F)FeAs (RE = La, Nd, Ce) and LaOFeP systems: possible incommensurate/stripe magnetism and superfluid density
• The two colors of MgB2
• Superconductivity in single crystals of LaFePO
• Correlation effects in the iron pnictides
• New insight into the physics of iron pnictides from optical and penetration depth data

Cited by in corpus (240)

• The Puzzle of High Temperature Superconductivity in Layered Iron Pnictides and Chalcogenides
• High-temperature superconductivity in iron-based materials
• Strong electronic correlations from Hund's coupling
• Electrodynamics of Correlated Electron Materials
• Kinetic frustration and the nature of the magnetic and paramagnetic states in iron pnictides and iron chalcogenides
• Antiferromagnetic order and spin dynamics in iron-based superconductors
• Light scattering and surface plasmons on small spherical particles
• Magnetism and its microscopic origin in iron-based high-temperature superconductors
• High Temperature Superconductivity in Iron Pnictides and Chalcogenides
• FeAs-based superconductivity: a case study of the effects of transition metal doping on BaFe2As2
• Electronic Structure Calculations with the Tran-Blaha Modified Becke-Johnson Density Functional
• Selective Mottness as a key to iron superconductors
• Comparison of Ab initio Low-Energy Models for LaFePO, LaFeAsO, BaFe2As2, LiFeAs, FeSe and FeTe: Electron Correlation and Covalency
• Ironing out the details of unconventional superconductivity
• Colloquium: Graphene spectroscopy
• Quantum phases driven by strong correlations
• Nematicity and quantum paramagnetism in FeSe
• Observation of Temperature-Induced Crossover to an Orbital-Selective Mott Phase in A${}_x$Fe${}_{2-y}$Se${}_2$ (A=K, Rb) Superconductors
• Orbital Order and Spontaneous Orthorhombicity in Iron Pnictides
• Strongly Correlated Materials
• Observation of universal strong orbital-dependent correlation effects in iron chalcogenides
• Strong electron correlations in the normal state of FeSe0.42Te0.58
• Phase diagram and Gap anisotropy in Iron-Pnictide Superconductors
• Space group symmetry, spin-orbit coupling and the low energy effective Hamiltonian for iron based superconductors
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• Electronic Structure Calculation by First Principles for Strongly Correlated Electron Systems
• Electron and hole Dirac cone states in-pairs in Ba(FeAs)${}_2$ confirmed by magnetoresistance
• Flat bands, strange metals, and the Kondo effect
• Electronic correlations and partial gap in the bilayer nickelate La${}_3$Ni${}_2$O${}_7$
• Band Narrowing and Mott Localization in Iron Oxychalcogenides La2O2Fe2O(Se,S)2
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• Dichotomy between large local and small ordered magnetic moment in Iron-based superconductors
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• Symmetry of spin excitation spectra in the tetragonal paramagnetic and superconducting phases of 122-ferropnictides
• U(1) Slave-spin theory and its application to Mott transition in a multi-orbital model for iron pnictides
• Electrodynamics of electron doped iron-pnictide superconductors: Normal state properties
• What makes the Tc of monolayer FeSe on SrTiO3 so high: a sign-problem-free quantum Monte Carlo study
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• Many-body effects in iron pnictides and chalcogenides -- non-local vs dynamic origin of effective masses
• Massless Leggett Mode in Three-band Superconductors with Time-Reversal-Symmetry Breaking
• Spin fluctuations in iron pnictides and chalcogenides: From antiferromagnetism to superconductivity
• Bad-metal behavior reveals Mott quantum criticality in doped Hubbard models
• Quantum criticality in the iron pnictides and chalcogenides
• Mott transition in Modulated Lattices and Parent Insulator of (K,Tl)yFexSe2 Superconductors
• Evidence for multiple superconducting gaps in optimally doped BaFe${}_{1.87}$Co${}_{0.13}$As${}_2$ from infrared spectroscopy
• Ab initio Evidence for Strong Correlation Associated with Mott Proximity in Iron-based Superconductors
• Electronic Evidence of an Insulator-Superconductor Transition in Single-Layer FeSe/SrTiO3 Films
• Orbital selective pairing and superconductivity in iron selenides
• Charge dynamics of the Co-doped BaFe${}_2$As${}_2$
• Orbital selectivity and emergent superconducting state from quasi-degenerate $s-$ and $d-$wave pairing channels in iron-based superconductors
• Hundness versus Mottness in a three-band Hubbard-Hund model: On the origin of strong correlations in Hund metals
• Quantum dynamical screening of the local magnetic moment in Fe-based superconductors
• Mott Transition in Multi-Orbital Models for Iron Pnictides
• In situ diffraction study of catalytic hydrogenation of VO2: Stable phases and origins of metallicity
• Electronic correlations and unusual superconducting response in the optical properties of the iron-chalcogenide FeTe0.55Se0.45
• Optical properties of BaFe${}_{2-x}$Co${}_x$As${}_2$
• Orbital-selective superconductivity, gap anisotropy and spin resonance excitations in a multiorbital t-J1-J2 model for iron pnictides
• Superconducting Properties of the $s^{\pm }$-wave state: Fe-based superconductors
• Optical response of correlated electron systems
• Optical properties of the infinite-layer La${}_{1-x}$Sr${}_x$NiO${}_2$ and hidden Hund's physics
• A perspective on pnictide superconductors
• Direct observation of a nodeless superconducting energy gap in the optical conductivity of iron-pnictides
• Temperature-induced band shift in ferromagnetic Weyl semimetal Co3Sn2S2
• Phase diagram of CeFeAs${}_{1-x}$P${}_x$O obtained from electric resistivity, magnetization, and specific heat measurements
• Anisotropy of Electrical Transport in Pnictide Superconductors Studied Using Monte Carlo Simulations of the Spin-Fermion Model
• Anomalous Raman scattering from phonons and electrons of superconducting FeSe${}_{0.82}$
• From antiferromagnetic insulator to correlated metal in pressurized and doped LaMnPO
• Fermiology, Orbital Order, Orbital Fluctuation and Cooper Pairing in Iron-based Superconductors
• Non-Thermal Emergence of an Orbital-Selective Mott Phase in FeTe${}_{1-x}$Se${}_x$
• Correlation-Driven Electronic Reconstruction in FeTe${}_{1-x}$Se${}_x$
• Superconductivity in Ce- and U-based "122" heavy-fermion compounds
• Calorimetric Evidence of Strong-Coupling Multiband Superconductivity in Fe(Te0.57Se0.43) Single Crystal
• Superconductivity and its mechanism in an ab initio model for electron-doped LaFeAsO
• Iron pnictide superconductors: Electrons on the verge
• Quantum Interactions in Topological R166 Kagome Magnet
• Superconductivity at the Border of Electron Localization and Itinerancy
• Doping dependence of spin fluctuations and electron correlations in iron pnictides
• Non-Fermi liquid behavior in a correlated flatband pyrochlore lattice
• Orbital selectivity enhanced by nematic order in FeSe
• Electron correlation in FeSe superconductor studied by bulk-sensitive photoemission spectroscopy
• Charge transport in the Hubbard model at high temperatures: triangular versus square lattice
• Electronic properties of 3d transitional metal pnictides : A comparative study by optical spectroscopy
• Optical study of RbV${}_3$Sb${}_5$: Multiple density-wave gaps and phonon anomalies
• Spin Dynamics of a J1-J2-K Model for the Paramagnetic Phase of Iron Pnictides
• The specific heat jump at the superconducting transition and the quantum critical nature of the normal state of Pnictide superconductors
• A Mott insulator continuously connected to iron pnictide superconductors
• Shining light on transition metal oxides: unveiling the hidden Fermi Liquid
• High energy pseudogap and its evolution with doping in Fe-based superconductors as revealed by optical spectroscopy
• Orbital-selective Mott phase in multiorbital models for iron pnictides and chalcogenides
• Weak spin interactions in Mott insulating La2O2Fe2OSe2
• Determination of the optical properties of La{2-x}Ba{x}CuO{4} for several dopings, including the anomalous x=1/8 phase
• Cavity superconductor-polaritons
• Low-temperature synthesis of SmFeAsO0.7F0.3 wires with high transport critical current density
• Lifshitz transition driven by spin fluctuations and spin-orbit renormalization in NaOsO${}_3$
• Spectroscopic and thermodynamic properties in a four-band model for pnictides
• Gap structure in the electron-doped Iron-Arsenide Superconductor Ba(Fe0.92Co0.08)2As2: low-temperature specific heat study
• Electronic correlations in iron-pnictide superconductors and beyond; what can we learn from optics
• Optical conductivity and Raman scattering of iron superconductors
• Optical spectroscopy study on single crystalline LaFeAsO
• Coexistence of Half-Metallic Itinerant Ferromagnetism with Local-Moment Antiferromagnetism in Ba{0.60}K{0.40}Mn2As2
• Orbital selectivity in electron correlations and superconducting pairing of iron-based superconductors
• Infrared evidence of a Slater metal-insulator transition in NaOsO3
• Orbital-selective superconductivity in the nematic phase of FeSe
• Effect of non-local correlations on the electronic structure of LiFeAs
• Critical current and vortex dynamics in single crystals of Ca(Fe${}_{1-x}$Co${}_x$)${}_2$As${}_2$
• Correlated electronic structures and unconventional superconductivity in bilayer nickelate heterostructures
• Superconductivity in Multi-orbital t-J1-J2 Model and its Implications for Iron Pnictides
• The role of 245 phase in alkaline iron selenide superconductors revealed by high pressure studies
• Optical properties and electronic correlations in La${}_3$Ni${}_2$O${}_7$ bilayer nickelates under high pressure
• Crystal, magnetic, and electronic structures, and properties of new BaMnPnF (Pn = As, Sb, Bi)
• Nonequilibrium Quasiparticle Relaxation Dynamics in Single Crystals of Hole and Electron doped BaFe${}_2$As${}_2$
• Specific heat of Ca${}_{0.32}$Na${}_{0.68}$Fe${}_2$As${}_2$ single crystals: unconventional s${}_{\pm }$ multi-band superconductivity with intermediate repulsive interband coupling and sizable attractive intraband couplings
• Observation of topological nodal-line semimetal in YbMnSb2 through optical spectroscopy
• Extended Drude model and role of interband transitions in the mid-infrared spectra of pnictides
• The magnetic phase diagram of an extended J1-J2 model on a modulated square lattice and its implications for the antiferromagnetic phase of KyFexSe2
• Quantum critical behavior of electrons at the edge of charge order
• Analysis of spin density wave conductivity spectra of iron pnictides in the framework of density functional theory
• Modeling Antiferromagnetic Phase in Iron Pnictides: Weakly Ordered State
• Measurement of the c-axis optical reflectance of AFe${}_2$As${}_2$ (A=Ba, Sr) single crystals: Evidence of different mechanisms for the formation of two energy gaps
• Anisotropic in-plane optical conductivity in detwinned Ba(Fe1-xCox)2As2
• Effects of Fermi-surface shrinking on the optical sum rule in pnictides
• The magnetic moment enigma in Fe-based high temperature superconductors
• Magnetism in parent Fe-chalcogenides: quantum fluctuations select a plaquette order
• Electronic correlation assisted ferroelectric metallic state in LiOsO${}_3$
• Long- to short-range magnetic order in fluorine-doped CeFeAsO
• Electronic correlations in the van der Waals ferromagnet Fe${}_3$GeTe${}_2$ revealed by its charge dynamics
• Optical probe of strong correlations in LaNiO${}_3$ thin films
• Phonon splitting and anomalous enhancement of infrared-active modes in BaFe${}_2$As${}_2$
• Multi-gap superconductivity in a BaFe1.84Co0.16As2 film from optical measurements at terahertz frequencies
• Optical properties of V2O3 in its whole phase diagram
• On infrared pseudogap in cuprate and pnictide high-temperature superconductors
• Electronic Structure and Mott Localization in Iron Deficient TlFe${}_{1.5}$Se${}_2$ with Superstructures
• Origin of the density wave instability in trilayer nickelate La${}_4$Ni${}_3$O${}_{10}$ revealed by optical and ultrafast spectroscopy
• Spin Dynamics of a $J_1-J_2$ Antiferromagnet and its Implications for Iron Pnictides
• Fermi surface topology of LaFePO and LiFeP
• Charge-Stripe Order in a Parent Compound of Iron-based Superconductors
• Coupling of electronic and magnetic properties in Fe1+y(Te1-xSex)
• Possible origin of the reduced magnetic moment in iron pnictides: A dynamical mean field theory study
• LDA+DMFT Spectral Functions and Effective Electron Mass Enhancement in Superconductor LaFePO
• Geometrical frustration effects on charge-driven quantum phase transitions
• Properties of a diagonal 2-orbital ladder model of the Fe-pnictide superconductors
• Strong electronic correlations in iron pnictides: Comparison of the optical spectra for BaFe2As2-related compounds
• Direct observation of a Fermi liquid-like normal state in an iron-pnictide superconductor
• Gap states in insulating LaMnPO${}_{1-x}$F${}_x$ (x = 0 - 0.3)
• Strong correlations and the search for high-Tc superconductivity in chromium pnictides and chalcogenides
• Orbital-dependent effects of electron correlations in microscopic models for iron-based superconductors
• Magnetic interactions in iron superconductors studied with a five-orbital model within the Hartree-Fock and Heisenberg approximations
• High-energy pseudogap in degenerate Hubbard model induced via Hund coupling
• The electronic instabilities of the Iron-based superconductors: a variational Monte-Carlo study
• ThFeAsN in Relation to Other Iron-Based Superconductors
• Impurity-induced bound states inside the superconducting gap of FeSe
• Theoretical Investigation of Optical Conductivity in Ba [Fe(1-x)Co(x)]2 As2
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• A view from inside iron-based superconductors
• Magnetic states of the five-orbital Hubbard model for one-dimensional iron-based superconductors
• Dielectric signature of charge order in lanthanum nickelates
• Detecting a preformed pair phase: The response to a pairing forcing field
• Optical spectroscopy study of Nd(O,F)BiS2 single crystals
• Quantum oscillations of the superconductor LaRu${}_2$P${}_2$ : comparable mass enhancement $\lambda \approx 1$ in Ru and Fe phosphides
• Ab-initio perspective on structural and electronic properties of iron-based superconductors
• Orbital density wave induced by electron-lattice coupling in orthorhombic iron pnictides
• Local Quantum Criticality of an Iron-Pnictide Tetrahedron
• Evolution of correlation strength in KxFe(2-y)Se2 superconductor doped with S
• Electronic Correlations and Evolution of the Charge-Density Wave in the Kagome Metals $A$V${}_3$Sb${}_5$ ($A$ = K, Rb, Cs)
• Synthesis, phase stability, structural and physical properties of 11-type iron chalcogenides
• Spectral weight transfer in strongly correlated Fe${}_{1.03}$Te
• Born effective charges and vibrational spectra in super and bad conducting metals
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• Spectral weight redistribution in (LaNiO3)n/(LaMnO3)2 superlattices from optical spectroscopy
• Iron-based superconductors: tales from the nuclei
• Magnetism in La2O3(Fe1-xMnx)2Se2 tuned by Fe/Mn ratio
• Ru-doping on iron based pnictides: the "unfolded" dominant role of structural effects for superconductivity
• Spin dynamics in electron-doped pnictide superconductors
• Effective Exchange Interactions for Bad Metals and Implications for Iron-based Superconductors
• Pressure Induced Enhancement of Superconductivity in LaRu2P2
• Fast recovery of the stripe magnetic order by Mn/Fe substitution in F-doped LaFeAsO superconductors
• Spin-one bilinear-biquadratic model on a star lattice
• On the Spatial Locality of Electronic Correlations in LiFeAs
• Phonon Anomalies, Orbital-Ordering and Electronic Raman Scattering in iron-pnictide Ca(Fe0.97Co0.03)2As2: Temperature-dependent Raman Study
• Origin of doping-induced suppression and reemergence of magnetism in LaFeAsO${}_{1-x}$H${}_x$
• Exchange striction driven magnetodielectric effect and potential photovoltaic effect in polar CaOFeS
• Structural, electronic, and dynamical properties of the tetragonal and collapsed tetragonal phases of KFe${}_2$As${}_2$
• Looking at the superconducting gap of iron pnictides
• Observation of an Emergent Coherent State in the Iron-Based Superconductor KFe${}_2$As${}_2$
• NMR study of electronic correlations in Mn-doped Ba(Fe1-xCox)2As2 and BaFe(As1-xPx)2
• Ising-nematic order in the bilinear-biquadratic model for the iron pnictides
• Optical properties of iron-based superconductor LiFeAs single crystal
• Orbital-Selective Superconductivity and the Effect of Lattice Distortion in Iron-Based Superconductors
• TAO pairing: a fully gapped pairing scenario for the Iron-Based Superconductors
• Elementary Excitations due to Orbital Degrees of Freedom in Iron Based Superconductors
• Optical properties of the iron-chalcogenide superconductor FeTe0.55Se0.45
• K2Mo3As3 is a Multi-Gap Electron-Phonon Superconductor
• Low quasiparticle coherence temperature in the one band-Hubbard model: A slave-boson approach
• Microscopic description of insulator-metal transition in high-pressure oxygen
• Magnetic excitations in ferro-pnictide materials controlled by a quantum critical point into hidden order
• Thermal and electrical transport in the spin density wave antiferromagnet CaFe${}_4$As${}_3$
• Magnetic neutron scattering studies on the Fe-based superconductor system Fe${}_{1+y}$Te${}_{1-x}$Se${}_x$
• Electrodynamics of BaFe2As2 from infrared measurements under pressure
• Tripling the critical temperature of KFe${}_2$As${}_2$ by carrier switch
• Scaling of the Fano effect of the in-plane Fe-As phonon and the superconducting critical temperature in Ba${}_{1-x}$K${}_x$Fe${}_2$As${}_2$
• Role of electric fields on enhanced electron correlation in surface-doped FeSe
• Electron Correlation and Spin Dynamics in Iron Pnictides and Chalcogenides
• Weak and strong electronic correlations in Fe superconductors
• Orbital-selective coherence-incoherence crossover and metal-insulator transition in Cu-doped NaFeAs
• Ultralow-dissipative conductivity by Dirac fermions in BaFe${}_2$As${}_2$
• Magnetic and Ising quantum phase transitions in a model for isoelectronically tuned iron pnictides
• Effect of electron correlations on spin excitation bandwidth in Ba${}_{0.75}$K${}_{0.25}$Fe${}_2$As${}_2$ as seen via time-of-flight inelastic neutron scattering
• Insulating Parent Phase and Distinct Doping Evolution to Superconductivity in Single-Layer FeSe/SrTiO3 Films
• Intrinsic charge dynamics in high-Tc AFeAs(O,F) superconductors
• Role of electron-electron interactions in the charge dynamics of rare-earth-doped CaFe2As2
• Anisotropic magnetic excitations of a frustrated bilinear-biquadratic spin model -- Implications for spin waves of detwinned iron pnictides
• Optical Study of BaFe${}_2$As${}_2$ under pressure: Coexistence of spin-density-wave gap and superconductivity
• Optical anisotropy of the kagome magnet FeSn: Dominant role of excitations between kagome and Sn layers
• A direct probe of the variability of Coulomb correlation in Fe-pnictide superconductors
• Interplay of $d$- and $p$-states in RbTi${}_3$Bi${}_5$ and CsTi${}_3$Bi${}_5$ flat-band kagome metals
• Many-body correlations brought to light in absorption spectra of diluted magnetic semiconductors
• Common effect of chemical and external pressures on the magnetic properties of $R$CoPO ($R$ = La, Pr, Nd, Sm). II
• Spin and charge susceptibilities of the two-orbital model within the cluster perturbation theory for Fe-based materials
• Electrodynamic properties of an artificial heterostructured superconducting cuprate
• The perils of minimal coupling to electromagnetic field in quantum many-body systems
• Effect of inelastic scattering on the nuclear magnetic relaxation rate 1/T1T in iron-based superconductors
• Spin dynamics in NaFeAs and NaFe${}_{0.53}$Cu${}_{0.47}$As probed by resonant inelastic X-ray scattering
• The magnetoresistance and Hall effect in CeFeAsO: a high magnetic field study
• Highly anisotropic Drude-weight-reduction and enhanced linear-dichroism in van der Waals Weyl semimetal Td-MoTe2 with coherent interlayer electronic transport
• Absence of strong magnetic fluctuations in the iron phosphide superconductors LaFePO and Sr2ScO3FeP
• Deviating band symmetries and many-body interactions in a model hole doped iron pnictide superconductor
• Near room-temperature ferromagnetism from double-exchange in the van der Waals material CrGeTe${}_3$: evidence from optical conductivity under pressure
• Spin-wave excitations in the SDW state of iron pnictides: a comparison between the roles of interaction parameters
• Uncovering double-stripe and plaquette antiferromagnetic states in the one-band Hubbard model on a frustrated square lattice
• Electronic layer decoupling driven by density-wave order in La${}_4$Ni${}_3$O${}_{10}$
• Flat Band Generation through Interlayer Geometric Frustration in Intercalated Transition Metal Dichalcogenides
• Unconventional superconductivity after the BCS paradigm and empirical rules for the exploration of high temperature superconductors
• Pressure Induced Superconductivity in the New Compound ScZrCo1-$\delta$
• Correlated Diskoid-like Electronic States
• Evolution of charge dynamics in FeSe${}_{1-x}$Te${}_x$: Effects of electronic correlations and nematicity
• Observation of Two Cascading Screening Processes in an Iron-based Superconductor
• A full gap above the Fermi level: the charge density wave of monolayer VS2
• Charge-localization-driven metal-insulator phase transition in layered molecular conductors