The Unprecedented Giant Coupling of Fe-spin State and the As-As Hybridization in Iron-Pnictide

Abstract

From first principles calculations we unravel surprisingly strong interactions between arsenic ions in iron-pnictides, the strength of which is controlled by the Fe-spin state. Reducing the Fe-magnetic moment, weakens the Fe-As bonding, and in turn, increases As-As interactions, causing giant reduction in the c-axis. For CaFe${}_2$As${}_2$ system, this reduction is as large as 1.4 Å. Since the large c-reduction has been recently observed only under high-pressure\cite{cTphase}, our results suggest that the iron magnetic moment should be present in Fe-pnictides at all times at ambient pressure. Finally, the conventional electron-phonon coupling in the collapsed phase of CaFe${}_2$As${}_2$ gives a maximum $T_c$ of 0.6 K and can not explain the $\sim 12$ K superconductivity observed in some experiments. Implications of these findings on the mechanism of superconductivity in iron-pnictides are discussed.

Published version with updated references. It has new results such as conventional e-ph coupling in the collapsed phase of CaFe2As2 gives a maximum Tc of 0.6 K and cannot explain the ~12 K superconductivity observed in some experiments. Implications of these findings on the mechanism of superconductivity in iron pnictides are discussed

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Cited by in corpus (17)

• Possible re-entrant superconductivity in EuFe2As2 under pressure
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• 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
• Electronic Structure of Fe-Based Superconductors
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• Effects of the magnetic orderings on the dynamical conductivity: optical investigations of EuFe${}_2$As${}_2$ single crystals
• Phonon anomalies in pure and underdoped R{1-x}K{x}Fe{2}As{2} (R = Ba, Sr) investigated by Raman light scattering
• Presure-Induced Superconducting State of Antiferromagnetic CaFe${}_2$As${}_2$
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• Successive phase transitions under high pressure in FeTe0.92
• Electronic structure of BaCu${}_2$As${}_2$ and SrCu${}_2$As${}_2$: sp-band metals
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• Anomalous electron-phonon interaction in doped LaOFeAs: a First Principles calculation
• Electronic band structures and intra-atomic interactions in layered quaternary oxyarsenides LaZnAsO and YZnAsO