A perspective on pnictide superconductors

Abstract

FeSe is employed as reference material to elucidate the observed high Tc superconducting behaviour of the related layered iron pnictides. The structural and ensuing semimetallic band structural forms are here rather unusual, with the resulting ground state details extremely sensitive to the precise shape of the Fe-X coordination unit. The superconductivity is presented as coming from a combination of Resonant Valence Bond (RVB) and Excitonic Insulator physics, and incorporating Boson-Fermion degeneracy. Although sourced in a very different fashion the latter leads to some similarites with the high temperature superconducting (HTSC) cuprates. The Excitonic Insulator behaviour sees SDW, CDW/PLD and superconductive instabilities all vie for ground state status. The conflict leads to a very sensitive and complex set of properties, frequently mirroring HTSC cuprate behaviour. The delicate balance between ground states is made particularly difficult to unravel by the micro-inhomogeneity of structural form which it can engender. It is pointed out that several other notable superconductors, layered in form, semimetallic with indirect overlap and possessing homopolar bonding, would look to fall into the same general category, beta-ZrNCl and MgB2 and the high-pressure forms of several elements, like sulphur, phosphorus, lithium and calcium, being cases in point.

53 pages, 11 figures

References in corpus (118)

• Superconductivity at 36 K in beta-Fe1.01Se with the compression of the interlayer separation under pressure
• Observation of Fermi-surface-dependent nodeless superconducting gaps in Ba0.6K0.4Fe2As2
• Density functional study of FeS, FeSe and FeTe: Electronic structure, magnetism, phonons and superconductivity
• Structural and magnetic phase diagram of CeFeAsO1-xFx and its relationship to high-temperature superconductivity
• Magnetism, superconductivity, and pairing symmetry in Fe-based superconductors
• To What Extent Iron-Pnictide New Superconductors Have Been Clarified: A Progress Report
• Extreme Sensitivity of Superconductivity to Stoichiometry in FeSe (Fe1+dSe)
• Effect of Structural Parameters on Superconductivity in Fluorine-Free LnFeAsO1-y (Ln=La,Nd)
• Is LaO${}_{1-x}$F${}_x$FeAs an electron-phonon superconductor ?
• Resonant Spin Excitation in the High Temperature Superconductor Ba0.6K0.4Fe2As2
• Nearly Isotropic superconductivity in (Ba,K)Fe2As2
• The Structural Phase Transition in FeSe (Fe1+dSe)
• Superconductivity up to 29 K in SrFe2As2 and BaFe2As2 at high pressures
• FeAs-based superconductivity: a case study of the effects of transition metal doping on BaFe2As2
• Why Does Undoped FeSe Become A High Tc Superconductor Under Pressure?
• Two-gap superconductivity in MgB${}_2$: clean or dirty?
• Electronic correlations in the iron pnictides
• Normal-State Spin Dynamics and Temperature-Dependent Spin Resonance Energy in an Optimally Doped Iron Arsenide Superconductor
• Effects of nematic fluctuations on the elastic properties of iron arsenide superconductors
• Coexistence of the spin-density-wave and superconductivity in the (Ba,K)Fe2As2
• Superconductivity up to 30 K in the vicinity of quantum critical point in BaFe${}_2$(As${}_{1-x}$P${}_x$)${}_2$
• Crystal structure of the new FeSe1-x superconductor
• Transition of stoichiometricSr2VO3FeAs to a superconducting state at 37.2 K
• Electronic structure of the iron-based superconductor LaOFeP
• Structure and superconductivity of LiFeAs
• Competition and coexistence of antiferromagnetism and superconductivity in underdoped Ba(Fe0.953Co0.047)2As2
• Similarities between structural distortions under pressure and chemical doping in superconducting BaFe2As2
• ${}^{75}$As NMR studies of superconducting LaO${}_{0.9}$F${}_{0.1}$FeAs
• Superconductivity in S-substituted FeTe
• Anisotropy in the electrical resistivity and susceptibility of superconducting BaFe${}_2$As${}_2$ single crystals
• Crystallographic Phase Transition and High-Tc Superconductivity in LaFeAsO:F
• Heat Conduction in the Vortex State of NbSe_2: Evidence for Multi-Band Superconductivity
• Superconductivity at 17 K in (Fe2P2)(Sr4Sc2O6): a new superconducting layered pnictide oxide with a thick perovskite oxide layer
• Electronic phase separation in the slightly underdoped iron pnictide superconductor Ba(1-x)K(x)Fe(2)As(2)
• Unconventional pairing in the iron arsenide superconductors
• Evidence for nodal superconductivity in LaFePO
• Bandwidth and Fermi surface of Iron-Oxypnictides: covalency and sensitivity to structural changes
• Pressure Induced Static Magnetic Order in Superconducting FeSe_1-x
• Fermi surface topology and low-lying quasiparticle dynamics of parent Fe${}_{1+x}$Te/Se Superconductor by orbital-polarization resolved ARPES
• Fermi surface topology and low-lying quasiparticle structure of magnetically ordered Fe1+xTe
• Fermi surface of superconducting LaFePO determined by quantum oscillations
• Pressure induced high-spin to low-spin transition in FeS evidenced by x-ray emission spectroscopy
• Complete pressure dependent phase diagrams for SrFe2As2 and BaFe2As2
• A Large Iron Isotope Effect in SmFeAsO1-xFx and Ba1-xKxFe2As2
• Thermal conductivity of single crystalline MgB_2
• Spin susceptibility, phase diagram, and quantum criticality in the electron-doped high Tc Superconductor Ba[Fe(1-x)Co(x)]2As2
• Low temperature specific heat of the hole-doped Ba_{0.6}K_{0.4}Fe_2As_2 single crystals and electron-doped SmFeAsO_{0.9}F_{0.1} samples
• Fully Gapped Superconducting State Based on a High Normal State Quasiparticle Density of States in Ba${}_{0.6}$K${}_{0.4}$Fe${}_2$As${}_2$ Single Crystals
• Specific heat jump at the superconducting transition temperature in Ba(Fe(1-x)Cox)2As2 and Ba(Fe(1-x)Nix)2As2 single crystals
• Synthesis, crystal structure and chemical stability of the superconductor FeSe_{1-x}
• Precise Pressure Dependence of the Superconducting Transition Temperature of FeSe: Resistivity and ^77Se--NMR Study
• Superfluid density and specific heat within self-consistent scheme for two-band superconductor
• Electron-lattice interaction and its impact on high Tc superconductivity
• Crystal orientation and thickness dependence of superconductivity on tetragonal FeSe1-x thin films
• Electronic Structure of the BaFe${}_2$As${}_2$ Family of Iron Pnictides
• High temperature superconductivity (Tc onset at 34K) in the high pressure orthorhombic phase of FeSe
• Strong Tc dependence for strained, epitaxial Ba(Fe1-xCox)2As2 thin films
• Abrupt Emergence of Pressure-Induced Superconductivity of 34 K in SrFe2As2: A Resistivity Study under Pressure
• Muon-spin rotation studies of SmFeAsO_0.85 and NdFeAsO_0.85 superconductors
• Temperature dependent photoemission on 1T-TiSe2: Interpretation within the exciton condensate phase model
• The London penetration depth in single crystals of Ba(Fe_{1-x}Co_x)_2As_2 at various doping levels
• Magnetic penetration depth of single crystal SmFeAsO_{1-x}F_y: a fully gapped superconducting state
• Intrinsic Properties of AFe2As2 (A = Ba, Sr) Single Crystal under Highly Hydrostatic Pressure Conditions
• The Stoichiometry of FeSe
• Strong-coupling Spin-singlet Superconductivity with Multiple Full Gaps in Hole-doped Ba${}_{0.6}$K${}_{0.4}$Fe${}_2$As${}_2$ Probed by Fe-NMR
• 75As NMR Study of Hole-Doped Superconductor Ba1-xKxFe2As2 (Tc = 38K)
• Superconducting and normal phases of FeSe single crystals at high pressure
• Pressure-Induced Effects on the Structure of the FeSe Superconductor
• Non-exponential London penetration depth in Ba${}_{1-}$K${}_x$Fe${}_2$As${}_2$ single crystals
• Fermi surface dichotomy of the superconducting gap and pseudogap in underdoped pnictides
• Anomalous metallic state in the vicinity of Metal to Valence Bond Solid insulator transition in LiVS2
• New iron-based arsenide oxides (Fe2As2)(Sr4M2O6)(M = Sc, Cr)
• Water-induced superconductivity in SrFe2As2
• The a-axis optical conductivity of detwinned ortho-II YBa_2Cu_3O_6.50
• Superconductivity, magnetism and crystal chemistry of Ba1-xKxFe2As2
• Optical spectroscopy of superconducting Ba{0.55}K{0.45}Fe2As2: evidence for strong coupling to low energy bosons
• Fermi surface of SrFe${}_2$P${}_2$ determined by de Haas-van Alphen effect
• Magnetic-superconducting phase boundary of SmFeAsO${}_{1-x}$F${}_x$ studied via muon spin rotation: Unified behavior in a pnictide family
• MuSR studies of RE(O,F)FeAs (RE = La, Nd, Ce) and LaOFeP systems: possible incommensurate/stripe magnetism and superfluid density
• Effects of Ru Doping on the Transport Behavior and Superconducting Transition Temperature of NdFeAsO0.89F0.11
• Effect of Uniaxial Stress for Pressure-Induced Superconductor SrFe_2As_2
• Topological change of the Fermi surface in ternary iron-pnictides with reduced c/a ratio: A dHvA study of CaFe2P2
• Determination of the Fermi Surface of MgB${}_2$ by the de Haas-van Alphen effect
• Lattice collapse and the magnetic phase diagram of Sr${}_{1-x}$Ca${}_x$Co${}_2$P${}_2$
• Antiferromagnetic fluctuations in the normal state of LiFeAs
• Charge order, metallic behavior and superconductivity in La_{2-x}Ba_xCuO_4 with x=1/8
• Pressure shift of the superconducting T_c of LiFeAs
• The pseudogap behavior in the stoichiometric FeSe superconductor (Tc~9.4 K)
• Correlations in a band insulator
• Spin Dynamics in Cuprates: Optical Conductivity of HgBa2CuO4
• Suppression of the structural phase transition and lattice softening in slightly underdoped Ba(1-x)K(x)Fe2As2 with electronic phase separation
• Superconductivity in LnFePO (Ln = La, Pr, and Nd) single crystals
• Resonance as a probe of the electron superconducting gap in BaFe1.9Ni0.1As2
• Electronic Structure of Superconducting FeSe Studied by High-Resolution Photoemission Spectroscopy
• Electronic properties of LaOFFeAs in the normal state probed by NMR/NQR
• Anomalous Pressure Dependence of the Superconducting Transition Temperature in FeSe1-x Studied by DC Magnetic Measurements
• In-plane optical conductivity of La${}_{2-x}$Sr${}_x$CuO${}_4$: Reduced superconducting condensate and residual Drude-like response
• Limits on the Superconducting Order Parameter in NdFeAsO${}_{1-x}$F${}_y$ from Scanning SQUID Microscopy
• Universal magnetic and structural behaviors in the iron arsenides
• Inelastic X-ray Scattering Study of superconducting SmFeAs(O${}_{1-x}$F${}_y$) Single Crystals: Evidence for Strong Momentum-Dependent Doping-Induced Renormalizations of Optical Phonons
• Doping dependence of upper critical field and Hall resistivity in LaFeAsO1-xFx
• Multi-band conductivity and multi-gap superconductivity in V3Si from optical measurements on films at terahertz frequencies
• On the correct formula for the lifetime broadened superconducting density of states
• Competing Phases, Strong Electron-Phonon Interaction and Superconductivity in Elemental Calcium under High Pressure
• Multi-Gap Superconductivity in MgB2: Magneto-Raman Spectroscopy
• Structure and Physical properties of New layered oxypnictides $S{r}_{4}S{c}_2{O}_6{M}_{2}A{s}_2$ (M=Fe and Co)
• 75As-NMR studies on La FeAsO1-xFx (x=0.14) under a pressure of 3GPa
• Magnetic characterization of undoped and 15%F doped LaFeAsO and SmFeAsO compounds
• Nodal Gap in Fe-Based Layered Superconductor LaO_0.9F_{0.1-delta}FeAs Probed by Specific Heat Measurements
• Novel results in STM, ARPES, HREELS, Nernst, neutron, Raman, and isotope substitution experiments and their relation to bosonic modes and charge inhomogeneity, from perspective of negative-Ueff boson-fermion modelling of HTSC
• Superconductivity in Undoped Single Crystals of BaFe2As2: Field and Current Dependence
• Mixtures of correlated bosons and fermions: Dynamical mean-field theory for normal and condensed phases
• Structural matters in HTSC; the origin and form of stripe organization and checker boarding
• Effect of electron-lattice interaction on the phase separation in strongly correlated electron systems with two types of charge carriers
• Field Dependent Superfluid Density in the Optimally Doped SmFeAsO_(1-x)F_y Superconductor
• Evolution with hole doping of the electronic excitation spectrum in the cuprate superconductors
• Mossbauer Spectroscopy Determination of iron foreign phases in the Superconducting Systems; RAsFeO1-x, RAsFeO1-xFx and Sr1-xKxFe2As2
• Magnetic and Superconducting Properties of Single Crystals of Fe${}_{1+\delta }$Te${}_{1-x}$Se${}_x$ System

Cited by in corpus (28)

• London Penetration Depth in Iron - based Superconductors
• New ternary ThCr2Si2-type iron-selenide superconducting materials: synthesis, properties and simulations
• Superconductivity in the iron selenide KxFe2Se2 (0 <= x <= 1)
• The intercalation chemistry of layered iron chalcogenide superconductors
• Electronic structure and Fermi surface of new K intercalated iron selenide superconductor KxFe2Se2
• Thin Film Growth and Device Fabrication of Iron-Based Superconductors
• Crystal Chemistry and Structural Design of Iron-Based Superconductors
• Microstructural magnetic phases in superconducting FeTe0.65Se0.35
• Crystal Structure of BaFe2Se3 as a Function of Temperature and Pressure: Phase Transition Phenomena and High-Order Expansion of Landau Potential
• Twisting of 2D kagomé sheets in layered intermetallics
• Search for pressure induced superconductivity in CeFeAsO and CeFePO iron pnictides
• Dynamics of Order Parameters near Stationary States in Superconductors with a Charge-Density Wave
• Stability, structural, elastic and electronic properties of polymorphs of the superconducting disilicide YIr2Si2
• Pressure-dependent magnetization and magnetoresistivity studies on the tetragonal FeS (mackinawite): revealing its intrinsic metallic character
• Quasiclassical description of a superconductor with a spin density wave
• Microstructural and transport properties of superconducting FeTe0.65Se0.35 crystals
• Local Structure of the Superconductor K0.8Fe1.6+xSe2: Evidence of Large Structural Disorder
• Incommensurate spin-density wave and multiband superconductivity in Na${}_x$FeAs as revealed by nuclear magnetic resonance
• Josephson-like spin current in junctions composed of antiferromagnets and ferromagnets
• The double life of electrons in magnetic iron pnictides, as revealed by NMR
• Realization of the $\pi$-state in junctions formed by multi-band superconductors with a spin-density-wave
• High pressure transport studies of the LiFeAs analogues CuFeTe2 and Fe2As
• Elastic properties and inter-atomic bonding in new superconductor KFe2Se2 from first principles calculations
• The Superconducting Transition Temperatures of Fe1+xSe1--y, Fe1+xSe1--yTey and (K/Rb/Cs)zFe2--xSe2
• Charge compensation and optimal stoichiometry in superconducting (Ca${}_x$La${}_{1-x}$)(Ba${}_{1.75-x}$La${}_{0.25+x}$)Cu${}_3$O${}_y$
• Time-dependent equation for the magnetic order parameter near the quantum critical point in multiband superconductors with a spin density wave
• Tunable superconductivity in Fe-pnictide heterointerfaces by diffusion control
• Electronic properties of new low-temperature superconductors: 3.3K (Ni2P2)(Sr4Sc2O6) and 2.7K (Ni2As2)(Sr4Sc2O6) from first principles