Regensburg 2013 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 12: Poster Session Superconductivity
TT 12.53: Poster
Monday, March 11, 2013, 15:00–19:00, Poster D
Paramagnetic Cooper pair breaking effect in α-(BEDT-TTF)2KHg(SCN)4 — •Michael Kunz1, Sebastian Jakob1, Werner Biberacher1, Karl Neumaier1, Harald Müller2, and Mark V. Kartsovnik1 — 1Walther-Meißner-Institut, Garching, Germany — 2European Synchrotron Radiation Facility, Grenoble, France
The organic charge transfer salt α-(BEDT-TTF)2KHg(SCN)4 is a quasi-two-dimensional metal consisting of conducting and insulating layers. At pressures above 2.5 kbar this compound features a low Tc (∼ 0.1 K) superconducting state with an unprecedentedly high anisotropy of the upper critical field depending on whether the magnetic field is oriented parallel or perpendicular to the conducting planes. This is due to a strong suppression of the superconducting shielding currents in the direction perpendicular to the layers. For an exact parallel field orientation the shielding currents become so weak that their effect is replaced by the Pauli paramagnetic effect as the main contribution to the Cooper pair breaking. Clear manifestations of the paramagnetic pair breaking can be seen in the temperature dependence as well as in the angular dependence of the critical field near parallel orientation. At the exact parallel field orientation, the theoretical Chandrasekhar-Clogston paramagnetic limit is exceeded by a factor of 1.3, most likely due to a strong electron-phonon coupling. From the analysis of the temperature dependence of the parallel critical field the Maki parameter can be determined.