X-ray spectra and electronic structure of FeAs superconductors

Abstract

The densities of the valence and conduction band electronic states of the newly discovered layered superconductors LaOFeAs, LaO${}_{0.87}$F${}_{0.13}$FeAs (Tc=26 K), SmO${}_{0.95}$F${}_{0.05}$FeAs and SmO${}_{0.85}$F${}_{0.15}$FeAs (Tc=43 K) are studied using soft X-ray absorption and emission spectroscopy combined with FP LAPW calculations of LaOFeAs, LaO${}_{0.875}$FeAs and LaO${}_{0.875}$F$0.125$FeAs. The Fe 3d-states are localized in energy near the top of the valence band and are partially hybridized with p-type O (2p), As (4p), and La (6p) states approximately 3 eV below the Fermi energy. The Fe L3 X-ray emission spectra do not show any features that would indicate the presence of the low Hubbard 3d-band or the quasiparticle peak that were predicted by the DMFT analysis of LaOFeAs. We can conclude that the LaOFeAs-type compounds do not represent strongly correlated systems. When either oxygen vacancies or fluorine dopants are included in numerical electronic structure calculations the width of O 2p-band decreases, but the distribution of Fe 3d-states is largely unaffected.

5 pages, 7 figures

References in corpus (14)

• Magnetic Order versus superconductivity in the Iron-based layered La(O1-xFx)FeAs systems
• Superconductivity at 43 K in Samarium-arsenide Oxides $SmFeAs{O}_{1-x}{F}_x$
• LaFeAsO${}_{1-x}$F${}_x$: A low carrier density superconductor near itinerant magnetism
• Superconductivity at 41 K and its competition with spin-density-wave instability in layered CeO${}_{1-x}$F${}_x$FeAs
• Superconductivity in iron-based F-doped layered quaternary compound Nd[O1-xFx]FeAs
• Very High Field Two-Band Superconductivity in LaFeAsO_0.89F_0.11
• Superconductivity at 25 K in hole doped $(L{a}_{1-x}S{r}_x)OFeAs$
• Correlated electronic structure of LaOFeAs
• Superconductivity at 52 K in iron-based F-doped layered quaternary compound Pr[O1-xFx]FeAs
• Proximity of antiferromagnetism and superconductivity in LaO${}_{1-x}$F${}_x$FeAs: effective Hamiltonian from ab initio studies
• Doping-dependent Phase Diagram of LaO{\it M}As ({\it M}=V--Cu) and Electron-type Superconductivity near Ferromagnetic Instability
• Electronic Structure and Electron Correlation in LaFeAsO_{1-x}F_x and LaFePO_{1-x}F_x
• Normal State Correlated Electronic Structure of Iron Pnictides
• Electromagnetic properties and electronic structure of iron-based layered superconductor LaOFeP

Cited by in corpus (16)

• Dynamical Mean-Field Theory within an Augmented Plane-Wave Framework: Assessing Electronic Correlations in the Iron Pnictide LaFeAsO
• Orbital Order and Spontaneous Orthorhombicity in Iron Pnictides
• Density Functional Study of Excess Fe in Fe${}_{1+x}$Te: Magnetism and Doping
• Electronic Structure of Fe-Based Superconductors
• Electronic structure of oxygen-free 38K superconductor Ba1-xKxFe2As2 in comparison with BaFe2As2 from first principles
• Point contact Andreev reflection spectroscopy of NdFeAsO_0.85
• Strength of correlations in pnictides and its assessment by theoretical calculations and spectroscopy experiments
• A high resolution, hard X-ray photoemission investigation of BaFe${}_2$As${}_2$: moderate influence of the surface and evidence for a low degree of Fe 3d - As 4p hybridization of the near-E${}_F$ electronic states
• Effect of 3d-doping on the electronic structure of BaFe2As2
• Coulomb Parameter U and Correlation Strength in LaFeAsO
• The magnetic moment enigma in Fe-based high temperature superconductors
• Coupling between 4f and itinerant electrons in SmFeAsO1-xFx (0.15 < x < 0.2) superconductors: an NMR study
• Electronic structure of new quaternary superconductors LaONiBi and LaOCuBi from first principles
• Properties of KCo${}_2$As${}_2$ and Alloys with Fe and Ru: Density Functional Calculations
• A direct probe of the variability of Coulomb correlation in Fe-pnictide superconductors
• Correlation effects in Ni 3d states of LaNiPO