Electronic structure of single-crystalline Sr(Fe${}_{1-x}$Co${}_x$)${}_2$As${}_2$ probed by x-ray absorption spectroscopy: Evidence for isovalent substitution of Fe${}^{2+}$ by Co${}^{2+}$

Abstract

The substitutional dependence of valence and spin-state configurations of Sr(Fe${}_{1-x}$Co${}_x$)${}_2$As${}_2$ ($x=$ 0, 0.05, 0.11, 0.17, and 0.38) is investigated with near-edge x-ray absorption fine structure at the $L_{2,3}$ edges of Fe, Co, and As. The present data provide direct spectroscopic evidence for an effectively isovalent substitution of Fe${}^{2+}$ by Co${}^{2+}$, which is in contrast to the widely assumed Co-induced electron-doping effect. Moreover, the data reveal that not only does the Fe valency remain completely unaffected across the entire doping range, but so do the Co and As valencies as well. The data underline a prominent role of the hybridization between (Fe,Co) 3$d_{xy}$, $d_{xz}$, $d_{yz}$ orbitals and As $4s/4p$ states for the band structure in $A$(Fe${}_{1-x}$Co${}_x$)${}_2$As${}_2$ and suggest that the covalency of the (Fe,Co)-As bond is a key parameter for the interplay between magnetism and superconductivity.

References in corpus (21)

• Superconductivity at 38 K in the iron arsenide (Ba1-xKx)Fe2As2
• 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
• Superconductivity at 22 K in Co-doped BaFe2As2 Crystals
• Thorium-doping induced superconductivity up to 56 K in Gd1-xThxFeAsO
• Superconductivity up to 29 K in SrFe2As2 and BaFe2As2 at high pressures
• Electronic Structure and Doping in BaFe${}_2$As${}_2$ and LiFeAs: Density Functional Calculations
• Superconductivity and Crystal Structures of (Ba1-xKx)Fe2As2 (x = 0 - 1)
• Superconductivity up to 30 K in the vicinity of quantum critical point in BaFe${}_2$(As${}_{1-x}$P${}_x$)${}_2$
• Electron-Hole Symmetry and Magnetic Coupling in Antiferromagnetic LaOFeAs
• Where Are the Extra d Electrons in Transition-Metal Substituted Fe Pnictides?
• Electronic Structure of Fe-Based Superconductors
• Hole and Electron Contributions to the Transport Properties of Ba(Fe_(1-x)Ru_x)_2As_2 Single Crystals
• Extremely high sensitivity to uniaxial stress in pressure induced superconductivity of BaFe2As2
• Coexistence and competition of magnetism and superconductivity on the nanometer scale in underdoped BaFe1.89Co0.11As2
• Magnetic ordering and structural distortion in Ru doped BaFe2As2 single crystals studied by Neutron and X-ray diffraction
• On the electronic structure of electron doped LaOFeAs as seen by X-ray absorption spectroscopy
• Probing the role of Co substitution in the electronic structure of iron-pnictides
• Pressure versus concentration tuning of the superconductivity in Ba(Fe(1-x)Cox)2As2
• Orbital Symmetry of Ba(Fe1-xCox)2As2 Superconductors Probed with X-ray Absorption Spectroscopy
• Effect of transition-metal substitution in iron-based superconductors

Cited by in corpus (6)

• Origin of charge transfer and enhanced electron-phonon coupling in single unit-cell FeSe films on SrTiO3
• Effect of weak disorder on the phase competition in iron pnictides
• Orbital localization and the role of the Fe and As $4p$ orbitals in BaFe${}_2$As${}_2$ probed by XANES
• The electronic structure of Co-substituted $\text{Fe}\text{Se}$ superconductor probed by soft X-ray spectroscopy and density functional theory
• Substitution of Ni for Fe in superconducting Fe${}_{0.98}$Te${}_{0.5}$Se${}_{0.5}$ depresses the normal-state conductivity but not the magnetic spectral weight
• Hard X-ray spectroscopy of the itinerant magnets $R$Fe${}_4$Sb${}_{12}$ ($R=$Na, K, Ca, Sr, Ba)