Regensburg 2002 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 17: Postersitzung II: Mesoskopische Systeme (1-19), Supraleiter: Theorie (20-26), Elektronenstruktur, Phononen, Tunneln, Ordnungsparameter (27-33), Schwere Fermionen, Kondo-Systeme (34-45)
TT 17.31: Poster
Mittwoch, 13. März 2002, 14:30–18:00, A
Specific heat and disorder in the mixed state of non-magnetic borocarbides — •D. Lipp1, M. Schneider2, A. Gladun2, S.-L. Drechsler3, J. Freudenberger3, G. Fuchs3, K. Nenkov3, K.-H. Müller3, T. Cichorek4, and P. Gegenwart4 — 1Institut für Halbleiter- und Mikrosystemtechnik, Technische Universität (TU) Dresden, D-01062 Dresden, Germany — 2Institut für Tieftemperaturphysik, TU Dresden, D-01062 Dresden, Germany — 3Institut für Festkörper- und Werkstofforschung, D-01171 Dresden, Germany — 4Max-Planck-Institut für Chemische Physik fester Stoffe, D-01187 Dresden, Germany
The temperature and magnetic field dependence of the specific heat cp(T,H) in the superconducting (sc) mixed state as well as the upper critical field Hc2(T) have been measured for polycrystalline YxLu1−xNi2B2C and Y(Ni1− yPty)2B2C samples. The linear-in-T electronic specific heat contribution γ (H) · T exhibits significant deviations from the usual linear-in-H law resulting in a disorder dependent negative curvature of γ (H). The Hc2(T) data point to the quasi-clean limit for (Y,Lu)-substitutions and to a transition to the quasi-dirty limit for (Ni,Pt)-substitutions. The γ(H) dependence is discussed in the unitary d-wave as well as in the quasi-clean s- wave limits. From a consideration of γ (H) data only, d-wave pairing cannot be ruled out.