title: Observation of the crossover from two-gap to single-gap superconductivity through specific heat measurements in neutron-irradiated MgB2.
abstract: We report specific heat measurements on neutron-irradiated MgB2 samples, for which the critical temperature is lowered to 8.7 K, but the superconducting transition remains extremely sharp, indicative of a defect structure extremely homogeneous. Our results evidence the presence of two superconducting gaps in the temperature range above 21 K, while single-gap superconductivity is well established as a bulk property, not associated with local disorder fluctuations, when Tc decreases to 11 K.
authors.affiliation: CNR-INFM-LAMIA, Dipartimento di Fisica, Università di Genova, Via Dodecaneso 33, 16146 Genova, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Putti
authors.forename: M
authors.initials: M
authors.lastname: Affronte
authors.forename: C
authors.initials: C
authors.lastname: Ferdeghini
authors.forename: P
authors.initials: P
authors.lastname: Manfrinetti
authors.forename: C
authors.initials: C
authors.lastname: Tarantini
authors.forename: E
authors.initials: E
authors.lastname: Lehmann