Regensburg 2010 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 9: SC: Poster Session
TT 9.16: Poster
Montag, 22. März 2010, 14:00–18:00, Poster A
Calorimetric investigations of HoNi2B2C — •R. Beyer1, T. Herrmannsdörfer1, O. Ignatchik1, D. Souptel2, G. Behr2, and J. Wosnitza1 — 1Hochfeld-Magnetlabor Dresden (HLD), Forschungszentrum Dresden-Rossendorf, 01328 Dresden, Germany — 2Institut für Festkörperforschung, IFW Dresden, 01069 Dresden, Germany
The rare-earth nickel borocarbides show an intriguing competition between magnetism and superconductivity. For HoNi2B2C, this leads to a rich phase diagram with superconducting and magnetic phase transitions. Besides these competing electronic interactions, also the nuclear magnetic moment of Holmium may influence the superconducting state due to a strong hyperfine-enhanced nuclear polarisation. In order to study this in more detail, we have performed high-resolution specific-heat measurements by use of a continuous relaxation-time method. While the superconducting transition at about 8 K results in a very small, but resolvable specific-heat feature, at lower temperatures there are at least three independent magnetic-ordering transitions. One shows a lambda-like anomaly with a small hysteresis indicating a first-order phase transition. Additionally, susceptibility measurements performed below 1K fully agree with specific heat data indicating a possible re-entrant phase transition driven by hyperfine enhanced nuclear magnetism. This work has been partially supported by EuroMagNET II.