Труды сотрудников института физики

/ F. . Hammerath [et al.] // Phys. Rev. B. - 2010. - Vol. 81, Is. 14. - Ст. 140504, DOI 10.1103/PhysRevB.81.140504. - Cited References: 52. - This work has been supported by the DFG, through FOR 538, SPP 1458 and Contract No. Be1749/12. G. L. acknowledges support from the A. v. Humboldt-Stiftung. M. M. K. acknowledges support from RFBR under Grant No. 09-02-00127, RAS program on "Low temperature quantum phenomena" and President of Russia MK-1683.2010.2. S. L. D. thanks H. Kontani, K. Kuroki, K. Kikoin, and M. Kulic for useful discussions. . - ISSN 1098-0121РУБ Physics, Condensed Matter

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.

/ D. . Parker [et al.] // Phys. Rev. B. - 2008. - Vol. 78, Is. 13. - Ст. 134524, DOI 10.1103/PhysRevB.78.134524. - Cited References: 35 . - ISSN 1098-0121РУБ Physics, Condensed Matter

Аннотация: Recently, several measurements of the nuclear spin-lattice relaxation rate T(1)(-1) in the superconducting Fe pnictides have been reported. These measurements generally show no coherence peak below T(c) and indicate a low-temperature power-law behavior, the characteristics commonly taken as evidence of unconventional superconductivity with lines of nodes crossing the Fermi surface. In this work we show that (i) the lack of a coherence peak is fully consistent with the previously proposed nodeless extended s(+/-)-wave symmetry of the order parameter (whether in the clean or dirty limit) and (ii) the low-temperature power-law behavior can be also explained in the framework of the same model but requires going beyond the Born limit.

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Держатели документа:
[Parker, D.
Korshunov, M. M.] Max Planck Inst Phys Komplexer Syst, D-01187 Dresden, Germany
[Parker, D.] Max Planck Inst Chem Phys Fester Stoffe, D-01187 Dresden, Germany
[Dolgov, O. V.] Max Planck Inst Festkorperforsch, D-70569 Stuttgart, Germany
[Korshunov, M. M.] RAS, Siberian Branch, LV Kirensky Phys Inst, Krasnoyarsk 660036, Russia
[Golubov, A. A.] Univ Twente, Fac Sci & Technol, NL-7500 AE Enschede, Netherlands
[Parker, D.
Mazin, I. I.] USN, Res Lab, Washington, DC 20375 USA
ИФ СО РАН
Max-Planck-Institut fur Physik Komplexer Systeme, D-01187 Dresden, Germany
Max-Planck-Institut fur Chemische Physik Fester Stoffe, D-01187 Dresden, Germany
Max-Planck-Institut fur Festkorperforschung, D-70569 Stuttgart, Germany
L.V. Kirensky Institute of Physics, Siberian Branch of RAS, 660036 Krasnoyarsk, Russian Federation
Faculty of Science and Technology, University of Twente, 7500 AE Enschede, Netherlands
Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, United States

Доп.точки доступа:
Parker, D.; Dolgov, O. V.; Korshunov, M. M.; Коршунов, Максим Михайлович; Golubov, A. A.; Mazin, I. I.

/ S. G. Ovchinnikov // J. Exp. Theor. Phys. - 2008. - Vol. 107, Is. 1. - P. 140-146, DOI 10.1134/S1063776108070145. - Cited References: 19. - The author is grateful to D. Homsky, G. Sawatzky, and M. Haverkort for fruitful discussions of results. This study was supported by the Russdian Foundation for Basic Research ( project no. 07-02-00226) and the Presidium of the Russian Academy of Sciences ( Program "Quantum Macrophysics"). This study was initiated during the author's work at the Kavli Institute for Theoretical Physics (University of California, Santa Barbara, USA) and supported by the NSF ( grant no. PHY05-51164). . - ISSN 1063-7761РУБ Physics, Multidisciplinary

Аннотация: The effect of spin crossovers in d (n) terms on the effective Hubbardparameter (U(eff)) determining the gap between the lower and upper Hubbard bands is analyzed using a many-electron approach to describe the electron structure of Mott insulators. A new mechanism of the insulator-metal transition is established for d(5) ions, which is related to a decrease in U(eff) caused by spin crossover. For other ions, the U (eff) value is either independent of pressure (d(2), d(4), d(7)) or it exhibits nonmonotonic growth (d(3), d(6), d(8)).

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Держатели документа:
[Ovchinnikov, S. G.] Russian Acad Sci, Siberian Branch, Kirensky Phys Inst, Krasnoyarsk 660036, Russia
[Ovchinnikov, S. G.] Siberian Fed Univ, Krasnoyarsk 660041, Russia
ИФ СО РАН
Kirensky Institute of Physics, Siberian Branch, Russian Academy of Sciences, Krasnoyarsk, 660036, Russian Federation
Siberian Federal University, Krasnoyarsk, 660041, Russian Federation

Доп.точки доступа:
Овчинников, Сергей Геннадьевич