Dresden 2009 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 5: Postersession Superconductivity: Materials - Fabrication and Properties

TT 5.12: Poster

Montag, 23. März 2009, 13:00–16:45, P1A

Multiband superconductivity in YNi₂B₂C single crystals studied by use of specific-heat measurements — •A. Bekkali^1,2, J. Wosnitza^1,2, M. Uhlarz¹, R. Beyer¹, M. Schneider³, G. Behr³, S.-L. Drechsler³, and G. Fuchs³ — ¹Institut Hochfeld-Magnetlabor Dresden, Forschungszentrum Dresden-Rossendorf, D-01314 Dresden, Germany — ²TU Dresden, Institut für Festkörperphysik, D-01062 Dresden, Germany — ³Leibniz-Institut für Festkörper- und Werkstoffforschung, D-01171 Dresden, Germany

We present new specific-heat data for two different YNi₂B₂C single crystals grown by a zone-melting method. The two samples (T_c,A=15.26(4) K, T_c,B=15.6(1) K) were studied in magnetic fields up to B=9 T in the temperature range from T=0.35… 20 K, using both a relaxation and a heat-pulse method. In the superconducting state (B=0) we find an uncommon dependence of the electronic contribution to the specific heat, C_el(T), strengthening the assumption of a multiband nature of the superconducting state of YNi₂B₂C. A quantitative analysis of C_el(T) evidences multiple electronic contributions from electrons with very different electron-phonon coupling strengths, thus exhibiting several different superconducting energy gaps Δ(T,B=0). This feature is in agreement with recent de Haas – van Alphen results [1] and point-contact spectroscopy data [2].

[1] B. Bergk et al., PRL 100 (2008) 257004.

[2] P. Raychaudhuri et al., Physica C 460-462 (2007) 95.