Аннотация: We report As-75 nuclear magnetic resonance measurements of the spin-lattice relaxation in the superconducting (SC) state of LaFeAsO0.9F0.1 and As-deficient LaFeAs1-delta O0.9F0.1. The temperature behavior of 1/T-1 below T-c changes drastically from a T-3 dependence for LaFeAsO0.9F0.1 to a T-5 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.
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Держатели документа:
Inst Solid State Res, D-01171 Dresden, Germany
Max Planck Inst Phys Komplexer Syst, D-01187 Dresden, Germany
Russian Acad Sci, Siberian Branch, LV Kirensky Phys Inst, Krasnoyarsk 660036, Russia
Institute for Solid State Research, IFW Dresden, P.O. Box 270116, D-01171 Dresden, Germany
Max-Planck-Institut fur Physik Komplexer Systeme, D-01187 Dresden, Germany
L.V. Kirensky Institute of Physics, Siberian Branch, Russian Academy of Sciences, 660036 Krasnoyarsk, Russian Federation
Department of Physics, University of Florida, Gainesville, FL 32611, United States
Доп.точки доступа:
Hammerath, F.; Drechsler, S. L.; Grafe, H. J.; Lang, G.; Fuchs, G.; Behr, G.; Eremin, I.; Korshunov, M. M.; Коршунов, Максим Михайлович; Buchner, B.