Speaker
Description
The magnitude and the temperature dependence of the superconducting order parameter $\Delta(T)$ of
single-crystals of Cd$_2$Re$_2$O$_7$ ($T_c$ = 1.02~K) was measured using point-contact
spectroscopy. 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.
$\Delta (T)$ increases steeply below the superconducting transition temperature of 1.02 K
and levels off below $\sim$0.8 K
at a value of 0.22(1) meV, $\approx $40 \% larger than the BCS value.
Our results 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 $\sim$0.8 K.
