Point-contact spectroscopy in neutron-irradiated (MgB2)-B-11 (Articolo in rivista)

Type
Label
  • Point-contact spectroscopy in neutron-irradiated (MgB2)-B-11 (Articolo in rivista) (literal)
Anno
  • 2006-01-01T00:00:00+01:00 (literal)
Alternative label
  • Daghero, D; Calzolari, A; Ummarino, GA; Tortello, M; Gonnelli, RS; Stepanov, VA; Tarantini, C; Manfrinetti, P; Lehmann, E (2006)
    Point-contact spectroscopy in neutron-irradiated (MgB2)-B-11
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • Daghero, D; Calzolari, A; Ummarino, GA; Tortello, M; Gonnelli, RS; Stepanov, VA; Tarantini, C; Manfrinetti, P; Lehmann, E (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroVolume
  • 74 (literal)
Note
  • ISI Web of Science (WOS) (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
  • Politecn Turin, Dipartimento Fis, I-10129 Turin, Italy; Politecn Turin, CNISM, I-10129 Turin, Italy; Russian Acad Sci, PN Lebedev Phys Inst, Moscow 119991, Russia; Univ Genoa, Dipartimento Fis, I-16146 Genoa, Italy; Univ Genoa, CNR, INFM, LAMIA, I-16146 Genoa, Italy; Univ Genoa, Dipartimento Chim & Chim Ind, I-16146 Genoa, Italy; Paul Scherrer Inst, Dept Spallat Neutron Source SINQ, CH-5232 Villigen, Switzerland (literal)
Titolo
  • Point-contact spectroscopy in neutron-irradiated (MgB2)-B-11 (literal)
Abstract
  • We report on recent results of point-contact spectroscopy measurements in (MgB2)-B-11 polycrystals irradiated at different neutron fluences up to Phi=1.4x10(20) cm(-2). The point contacts were made by putting a small drop of Ag paint-acting as the counterelectrode-on the cleaved surface of the samples. The gap amplitudes were extracted from the experimental conductance curves, showing Andreev-reflection features, through a two-band Blonder-Tinkham-Klapwijk fit and reported as a function of the Andreev critical temperature of the junctions, T-c(A). The resulting Delta(sigma)(T-c(A)) and Delta(pi)(T-c(A)) curves show a clear merging of the gaps when T-c(A)similar or equal to 9 K that perfectly confirms the findings of specific-heat measurements in the same samples. Anomalous contacts with T-c(A)> T-c (being T-c the bulk critical temperature) were often obtained, particularly in samples irradiated at very high fluences. Their fit gave a different dependence of Delta(pi) on T-c(A). The possible origin of these contacts is discussed in terms of local current-induced annealing and/or nanoscale inhomogeneities observed by STM in the most irradiated samples. (literal)
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