Strong coupling and double-gap density of states in superconducting MgB2 (Articolo in rivista)

Type
Label
  • Strong coupling and double-gap density of states in superconducting MgB2 (Articolo in rivista) (literal)
Anno
  • 2002-01-01T00:00:00+01:00 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#doi
  • 10.1209/epl/i2002-00415-5 (literal)
Alternative label
  • Giubileo, F; Roditchev, D; Sacks, W; Lamy, R; Klein, J (2002)
    Strong coupling and double-gap density of states in superconducting MgB2
    in Europhysics letters (Print)
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • Giubileo, F; Roditchev, D; Sacks, W; Lamy, R; Klein, J (literal)
Pagina inizio
  • 764 (literal)
Pagina fine
  • 770 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroVolume
  • 58 (literal)
Rivista
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#pagineTotali
  • 7 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroFascicolo
  • 5 (literal)
Note
  • ISI Web of Science (WOS) (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
  • PRES University Sorbonne Paris Cite; Pierre & Marie Curie University - Paris 6; Centre National de la Recherche Scientifique (CNRS); University of Salerno; University of Salerno (literal)
Titolo
  • Strong coupling and double-gap density of states in superconducting MgB2 (literal)
Abstract
  • Using scanning tunneling spectroscopy at T = 4.2 K, we perform simultaneously the topographic imaging and the quasiparticle density of states (DOS) mapping in granular MgB2. We observe a new type of spectrum, showing a pronounced double gap, with the magnitudes of Delta(S) = 3.9 meV and Delta(L) = 7. 5 meV, i.e. well below and well above the BCS limit. The largest gap value gives the ratio 2Delta(L)/k(B)T(C) = 4.5, which implies strong electron-phonon coupling. Other superconducting regions are found to have a characteristic BCS-shaped DOS. However, the variation of the spectral shape and lower gap widths, from 2.0 meV to 6.5 meV, indicate the importance of surface inhomogeneity and proximity effects in previously published tunneling data. Our finding gives no evidence for any important gap anisotropy. Instead, it strongly supports the multiple-gap scenario in MgB2 in the clean limit, and the single-gap scenario in the dirty limit. (literal)
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