15 research outputs found
Evidence for Single-gap Superconductivity in Mg(B_{1-x}C_x)_2 Single Crystals with x=0.132 from Point-Contact Spectroscopy
We report the results of the first directional point-contact measurements in
Mg(B_{1-x}C_{x})_2 single crystals with 0.047 <= x <= 0.132. The two-gap
superconductivity typical of MgB_2 persists up to x=0.105. In this region, the
values of the gaps Delta_{sigma} and Delta_{pi} were determined by fitting the
Andreev-reflection conductance curves with a two-band Blonder-Tinkham-Klapwijk
(BTK) model, and confirmed by the single-band BTK fit of the sigma- and pi-band
conductances, separated by means of a magnetic field. At x=0.132, when T_{c}=19
K, we clearly observed for the first time the merging of the two gaps into one
of amplitude Delta~3 meV.Comment: 5 pages, 5 figures. One figure and one panel added; text and
discussion update
Point-Contact Spectroscopy in MgB_2: from Fundamental Physics to Thin-Film Characterization
In this paper we highlight the advantages of using point-contact spectroscopy
(PCS) in multigap superconductors like MgB_2, both as a fundamental research
tool and as a non-destructive diagnostic technique for the optimization of
thin-film characteristics. We first present some results of crucial fundamental
interest obtained by directional PCS in MgB_2 single crystals, for example the
temperature dependence of the gaps and of the critical fields and the effect of
a magnetic field on the gap amplitudes. Then, we show how PCS can provide
useful information about the surface properties of MgB_2 thin films (e.g. Tc,
gap amplitude(s), clean or dirty-limit conditions) in view of their
optimization for the fabrication of tunnel and Josephson junctions for
applications in superconducting electronics.Comment: 11 pages, 7 figures; Proceedings of 6th EUCAS Conference (14-18
September 2003, Sorrento - Italy