The role of disorder in superconducting magnesium diboride MgB2 policrystalline films is investigated in the high frequency range by a coplanar microwave resonator technique. Two sources of disorder are considered, heavy-ion irradiation damage and sample ageing. Microwave measurements are analyzed in the framework of the two-gap model with strong interband scattering contribution. It turns out that disorder enhancement increases the interband scattering rate, resulting in a reduction of the surface resistance at low temperatures, due to a slight increase of the gap. Moreover, increasing disorder at grain boundaries induces a nonmonotonic residual surface resistance, showing the features of a resistive behavior for the highest disorder level. Finally, the effects of the different kinds of disorder on the intrinsic and on the grain-boundary properties of the MgB2 films are compared and discussed.
Effects of disorder on the microwave properties of MgB2 polycrystalline films / G. GHIGO; UMMARINO G.A; R. GERBALDO; L. GOZZELINO; F. LAVIANO; E. MEZZETTI. - In: PHYSICAL REVIEW. B, CONDENSED MATTER AND MATERIALS PHYSICS. - ISSN 1098-0121. - 74(2006), pp. 184518-1-184518-6. [10.1103/PhysRevB.74.184518]
|Titolo:||Effects of disorder on the microwave properties of MgB2 polycrystalline films|
|Data di pubblicazione:||2006|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1103/PhysRevB.74.184518|
|Appare nelle tipologie:||1.1 Articolo in rivista|