Superconducting properties of a textured NbN film from 93Nb NMR relaxation and magnetization measurements (Articolo in rivista)

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  • Superconducting properties of a textured NbN film from 93Nb NMR relaxation and magnetization measurements (Articolo in rivista) (literal)
Anno
  • 2009-01-01T00:00:00+01:00 (literal)
Alternative label
  • Lascialfari, A; Rigamonti, A; Bernardi, E; Corti, M; Gauzzi, A; and Villegier, JC (2009)
    Superconducting properties of a textured NbN film from 93Nb NMR relaxation and magnetization measurements
    in Physical review. B, Condensed matter and materials physics
    (literal)
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  • Lascialfari, A; Rigamonti, A; Bernardi, E; Corti, M; Gauzzi, A; and Villegier, JC (literal)
Pagina inizio
  • 104505 (literal)
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  • 80 (literal)
Rivista
Note
  • ISI Web of Science (WOS) (literal)
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  • Dipartimento di Fisica A.Volta, CNR-INFM and Unità CNISM, Università di Pavia, Via Bassi 6, I-27100 Pavia, Italy; Dipartimento di Scienze Molecolari Applicate ai Biosistemi, Università di Milano, via Trentacoste 2, I-20134 Milano, Italy; S3-CNR-INFM, 41100 Modena, Italy; IMPMC, Universitè Pierre et Marie Curie-Paris 6-CNRS, 4, place Jussieu, 75252 Paris, France; CEA, INAC, SPSMS, 17 rue des Martyrs, 38054 Grenoble Cedex 9, France (literal)
Titolo
  • Superconducting properties of a textured NbN film from 93Nb NMR relaxation and magnetization measurements (literal)
Abstract
  • Primarily motivated by the similarities between the underdoped superconducting cuprates and the granular systems in regards of electric conductivity, phase fluctuations of the order parameter, and nuclear spin-lattice relaxation, a study has been carried out in a NbN(111) textured film at controlled granularity by means of superconducting quantum interference device magnetization and 93Nb NMR measurements. The Meissner diamagnetism in zero-field-cooling and field-cooling conditions and for different orientation of the magnetic field and the isothermal magnetization curves around the superconducting transition temperature Tc, are studied. 93Nb spectra and relaxation measurements have been performed for two values of the external magnetic field in parallel and perpendicular geometry, in the temperature range 4-300 K. In the superconducting phase the experimental findings for the textured film are similar to the one in bulk NbN. The nuclear spin-lattice relaxation process is the same as in bulk NbN in the temperature range 50-300 K, confirming a dominant contribution to the density of states at the Fermi energy arising from the Nb 4d band. At variance, on cooling from about 40 K down to Tc (H), the 93Nb relaxation rate in the film dramatically departs from the expected behavior for the Fermi gas and mimics the opening of a spin gap. The interpretation of the spin-gap opening in terms of depletion in the density of states at the Fermi energy can justify the anomalous temperature behavior of the 93Nb relaxation rate on approaching Tc (H) from above. The experimental findings suggest the occurrence of superconducting fluctuations (density-of-states term) in one-dimensional regime, coupled to a reduction in the time of flight of the electrons, both effects being related to the granularity. The data also suggest that the spin-gap phase in underdoped cuprates could be connected more to granularity, rather than to exotic mechanisms of magnetic origin. (literal)
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