Unusual disorder effects in superconducting LaFeAs1−δO0.9F0.1 as revealed by A75s NMR spectroscopy
F. Hammerath, S.-L. Drechsler, H.-J. Grafe, G. Lang, G. Fuchs, G. Behr, I. Eremin, M. M. Korshunov, B. Büchner
DOI 10.1103/PhysRevB.81.140504 · Physical Review B
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Abstract
We report A75s nuclear magnetic resonance measurements of the spin-lattice relaxation in the superconducting (SC) state of LaFeAsO0.9F0.1 and As-deficient LaFeAs1−δO0.9F0.1. The temperature behavior of 1/T1 below Tc changes drastically from a T3 dependence for LaFeAsO0.9F0.1 to a T5 dependence for the As-deficient sample. These results, together with the previously reported unexpected increase in Tc and the slope of the upper critical field near Tc for the As-deficient sample, are discussed in terms of nonuniversal SC gaps in Fe pnictides and the effect of As deficiency as an exotic case where nonmagnetic “smart” impurities even stabilize an s±-wave superconductor or within a scenario of a disorder-driven change to s++ superconductivity.
Source-reported materials — not catalogue approval
| Formula | Reported Tc (K) | Pressure (GPa) | Type |
|---|---|---|---|
| LaFeAsO0.9F0.1 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 26.8 | Pressure not reported | unknown |
| LaFeAsO0.9F0.1 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 26.8 | Pressure not reported | unknown |
| LaFeAs1-δO0.9F0.1 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 28.5 | Pressure not reported | unknown |
| LaFeAs1-δO0.9F0.1 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 28.5 | Pressure not reported | unknown |
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