Berlin 2005 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 18: Superconductivity - Properties, Electronic Structure, Order Parameter II
TT 18.6: Vortrag
Montag, 7. März 2005, 11:30–11:45, TU H2053
Multi-band influence on superconductivity in HoNi2B2C — •A. Wälte1, G. Fuchs1, Yu.G. Naidyuk2, K. Nenkov1, S.-L. Drechsler1, D. Souptel1, H. Rosner3, J. Freudenberger1, K.-H. Müller1, G. Behr1, and L. Schultz1 — 1Institut für Festkörper- und Werkstoffforschung Dresden, Helmholtzstr. 20, D-01171 Dresden — 2B. Verkin Institute for Low Temperature Physics and Engineering, National Academy of Sciences of Ukraine, 47 Lenin Ave., 61103 Kharkiv, Ukraine — 3MPI CPFS Dresden, Nöthnitzer Str. 40, D-01187 Dresden
Rare-earth nickel borocarbides RNi2B2C reveal, depending on the rare-earth R, superconductivity, magnetism or even a mixture of these competing phenomena [1]. The reduction of the superconducting ordering temperature Tc by magnetic pair-breaking fairly follows the Abrikosov-Gorkov model. However, details of the influence of magnetism on the electron system are not yet well understood. From specific heat measurements and point-contact spectroscopy on HoNi2B2C the phonon density of states F(ω) and the spectral function α2F(ω) have been extracted. The characteristic phonon frequency ωln≈180 K is similar to ωln of non-magnetic LuNi2B2C. Comparing the specific heat jumps of both compounds, an unexpectedly strong deviation from the Abrikosov-Gorkov expectation for HoNi2B2C is found. A possible explanation is the different influence of pair-breaking on different electron bands.
[1] R.J. Cava et al., Nature 367, January 1994.