Regensburg 2016 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 6: Superconductivity: Properties and Electronic Structure

TT 6.5: Vortrag

Montag, 7. März 2016, 11:00–11:15, H19

Cd₂Re₂O₇: Temperature dependence of the superconducting order parameter and the effect of quasiparticle self-energy — F. S. Razavi¹, Y. Rohanizadegan¹, M. Hajialamdari¹, M. Reedyk¹, B. Mitrovic¹, and •R. K. Kremer² — ¹Department of Physics, Brock University, St. Catharines, ON L2S 3A1, Canada — ²Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, 70569 Stuttgart, Germany

The temperature dependence and the magnitude of the superconducting order parameter of single crystals of Cd₂Re₂O₇ (T_c = 1.02 K) were measured using soft point-contact spectroscopy. The order parameter, Δ(T), increases steeply below the superconducting transition temperature and levels off below ∼ 0.8 K at a value of 0.22(1) meV, about 40 % larger than the BCS value. Our findings indicate the presence of a strong electron-phonon interaction and an enhanced quasiparticle damping and may be related to a possible phase transition within the superconducting region at ∼ 0.8 K. In order to fit the conductance spectra and to extract the order parameter at different temperatures we generalized the Blonder-Tinkham-Klapwijk theory by including the self-energy of the quasiparticles into the Bogoliubov equations. This modification enabled excellent fits of the conductance spectra.