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| Ertürk, Emre |
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| Azevedo, Nuno Monteiro |
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Wurmehl, Sabine
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Publications (9/9 displayed)
- 2023Phase transformation in Mn3Ga considering different degrees of deformationcitations
- 2020Filled carbon nanotubes as anode materials for lithium-ion batteriescitations
- 2020Pulsed laser deposition of Fe-oxypnictides : Co- and F-substitutioncitations
- 2019Structure-property relationship of Co 2 MnSi thin films in response to He + -irradiation
- 2016Hall-plot of the phase diagram for Ba(Fe1-xCox)2As2citations
- 2016Hall-plot of the phase diagram for Ba(Fe1−xCox)2As2
- 2015Interface control by homoepitaxial growth in pulsed laser deposited iron chalcogenide thin films
- 2011As-vacancies, local moments, and Pauli limiting in LaO_0.9F_0.1FeAs_(1-delta) superconductorscitations
- 2009Off-stoichiometry in Co2FeSi thin films sputtered from stoichiometric targets revealed by nuclear magnetic resonancecitations
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document
As-vacancies, local moments, and Pauli limiting in LaO_0.9F_0.1FeAs_(1-delta) superconductors
Abstract
We report magnetization measurements of As-deficient LaO_0.9F_0.1FeAs_1-delta (delta about 0.06) samples with improved superconducting properties as compared with As-stoichiometric optimally doped La-1111 samples. In this As-deficient system with almost homogeneously distributed As-vacancies (AV), as suggested by the (75)As-nuclear quadrupole resonance (NQR) measurements,we observe a strong enhancement of the spin-susceptibility by a factor of 3-7. This observation is attributed to the presence of an electronically localized state around each AV, carrying a magnetic moment of about 3.2 mu_Bohr per AV or 0.8 mu_Bohr/Fe atom. From theoretical considerations we find that the formation of a local moment on neighboring iron sites of an AV sets in when the local Coulomb interaction exceeds a critical value of about 1.0 eV in the dilute limit. Its estimated value amounts to ~ 2.5 eV and implies an upper bound of ~ 2 eV for the Coulomb repulsion at Fe sites beyond the first neighbor-shell of an AV. Electronic correlations are thus moderate/weak in doped La-1111. The strongly enhanced spin susceptibility is responsible for the Pauli limiting behavior of the superconductivity that we observe in As-deficient LaO_0.9F_0.1FeAs_1-delta. In contrast, no Pauli limiting behavior is found for the optimally doped, As-stoichiometric LaO_0.9F_0.1FeAs superconductor in accord with its low spin susceptibility. ; Comment: 11 pages, 9 figures