Dresden 2006 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 7: Superconductivity & Solids At Low Temperature - Poster Session
TT 7.4: Poster
Montag, 27. März 2006, 14:00–17:45, P1
Magnetic quantum oscillations in the normal and superconducting state of nonmagnetic borocarbides — •O. Ignatchik1, B. Bergk2, M. Jäckel2, J. Wosnitza1, D. Souptel3, G. Behr3, and P. C. Canfield4 — 1Dresden High Magnetic Field Laboratory, Forschungszentrum Rossendorf, 01314 Dresden — 2Institut für Festkörperphysik, Technische Universität Dresden, D-01062 Dresden — 3Leibniz-Institut für Festkörper- und Werkstofforschung, D-01069 Dresden — 4Condensed Matter Physics, Ames Laboratory, Ames, Iowa 50011, USA
We report on de Haas-van Alphen (dHvA) investigations of the nonmagnetic borocarbides YNi2B2C and LuNi2B2C. The measurements were carried out on high-quality single crystals by the torque method in magnetic fields up to 30 T. In the normal state the Fermi-surface topology has been analysed. In comparison with band-structure calculations several deviations are determined. Below the upper critical field, Bc2, in the vortex state an additional damping of the dHvA amplitudes appears. This damping is caused by the evolution from of the superconducting gap parameter. Concerning these topics we observe strong differences between differently grown crystals. The crystals produced by a zone-melting method show an abrupt vanishing of the dHvA signal at the upper critical field Bc2. In contrast, the flux grown crystals display a broader phase transition combined with a continuous decrease of the dHvA amplitude.