Bonura, M; Gallitto, AA; Vigni, ML; Ferdeghini, C; Tarantini, C
"[Bonura, M.; Gallitto, A. Agliolo; Vigni, M. Li] Univ Palermo, CNISM, I-90123 Palermo, Italy; [Bonura, M.; Gallitto, A. Agliolo; Vigni, M. Li] Univ Palermo, Dipartimento Sci Fis Astron, I-90123 Palermo, Italy; [Ferdeghini, C.; Tarantini, C.] Univ Genoa, CNR, INFM, LAMIA, I-16146 Genoa, Italy; [Ferdeghini, C.; Tarantini, C.] Univ Genoa, Dipartimento Fis, I-16146 Genoa, Italy
"We report on the microwave surface resistance of two polycrystalline (MgB2)-B-11 samples; one consists of pristine material, the other has been irradiated at very high neutron fluence. It has already been reported that in the strongly irradiated sample the two gaps merge into a single value. The mw surface resistance has been measured in the linear regime as a function of the temperature and the DC magnetic field, at increasing and decreasing fields. The results obtained in the strongly irradiated sample are quite well justified in the framework of a generalized Coffey and Clem model, in which we take into account the field distribution inside the sample due to the critical state. The results obtained in the pristine sample show several anomalies, especially at low temperatures, which cannot be justified in the framework of standard models for the fluxon dynamics. Only at temperatures near T-c and for magnetic fields greater than 0.5H(c2)(T) the experimental data can quantitatively be accounted for by the Coffey and Clem model, provided that the upper-critical-field anisotropy is taken into due account."
POINT-CONTACT SPECTROSCOPY, II SUPERCONDUCTORS, SINGLE-CRYSTALS, CRITICAL-STATE, MIXED-STATE
Tarantini Chiara, Ferdeghini Carlo
CNR authors
CNR institutes
External IDs
CNR OAI-PMH: oai:it.cnr:prodotti:3910