Berlin 2018 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 5: f-Electron Systems and Heavy Fermions I

TT 5.8: Hauptvortrag

Montag, 12. März 2018, 11:30–12:00, H 3005

Superconductivity in YbRh₂Si₂ — •Erwin Schuberth — Technische Universität München

Our recent experiments on YbRh₂Si₂ showed - aside from the well known antiferromagnetic transition at 70 mK - two new phases below 10 mK and 2 mK respectively[1]. The latter is practically coinciding with superconductivity. Evidence for these findings came from magnetic susceptibility measurements, dc as well as ac, performed at the Walther-Meissner Institut in Garching. The 2mK A-phase transition is a hybrid electronic-nuclear spin transition and it extends to fields of 23 mT where it is suppressed to below our detection limit of 800 µK. In addition, specific heat data show, that at this transition a large entropy is involved coming from the nuclear spins of the Yb isotopes. Here we present additional, unpublished results around and below this temperature up to the Quantum Critical Point at 60 mT. Also, we re-analyzed previous data on the magnetic susceptibility of CeCu₆ taken in Garching and Cornell in 1994 [2]. The results are very similar to those of YbRh₂Si₂ and it is very likely that the same mechanism holds in both systems.
E. Schuberth et al., Science 351, 485 (2016)
C. Jin et al., Physica B 194-196, 207-208 (1994)