Aluminum and carbon substitution in MgB2. Electron doping and scattering effects

TitleAluminum and carbon substitution in MgB2. Electron doping and scattering effects
Publication TypeJournal Article
Year of Publication2007
AuthorsSamuely P, Szabo P, Pribulova Z, Angst M, Bud'ko SL, Canfield PC, Klein T, Lyard L, Marcus J, Marcenat C, Kang BW, Kim HJ, Lee HS, Lee HK, Lee SI
Journal TitlePhysica C-Superconductivity and Its Applications
Date PublishedSep
Type of ArticleProceedings Paper
ISBN Number0921-4534
Accession NumberISI:000249870500024
Keywordselectron doping, scattering effects, two-band/two-gap superconductivity

The point-contact spectroscopy is used to address the evolution of two superconducting energy gaps in the Al- and C-doped magnesium diboride polycrystals and single crystals with T-c's from 39 to 22 K prepared by different techniques. The obtained evolution of two gaps does not show any anomalous behavior but can be consistently described by the combination of the (prevailing) band filling effect and a (minor) increased interband scattering as proposed by Kortus et al. [Kortus et al., Phys. Rev. Lett. 94 (2005) 027002]. The approaching of two gaps is stronger in the Al-doped systems but interband scattering is still not large enough to merge two gaps. The full merging can expected only for higher dopings with T-c's below 10-15 K. In-magnetic-field measurements are used to analyze the intraband scatterings introduced by these two substitutions. It is shown that the carbon doping introduces significant disorder mainly by decreasing the diffusion coefficient in the pi band while the Al substitution leaves the samples in the clean limit. (c) 2007 Elsevier B.V. All rights reserved.

Alternate JournalPhysica C