Resistivity study of RuSr₂GdCu₂O₈ superconductor

Abstract

The results of Point Contact Andreev Reflection Spectroscopy on polycrystalline RuSr2GdCu2O8 pellets are presented. The wide variety of the measured spectra are all explained in terms of a modified BTK model considering a d-wave symmetry of the superconducting order parameter. Remarkably low values of the energy gap ∆ = (2.8 ± 0.2)meV and of the 2∆/kBTc ≃ 2 ratio are inferred. From the temperature evolution of the dI/dV vs V characteristics we extract a sublinear temperature dependence of the superconducting energy gap. The magnetic field dependence of the conductance spectra at low temperatures is also reported. From the ∆ vs H evolution, a critical magnetic field Hc 2 ≃ 30T is inferred. To properly explain the curves showing gap-like features at higher voltages, we consider the formation of a Josephson junction in series with the Point Contact junction, as a consequence of the granularity of the sample.

Synthesis and Characterization of RuSr2R1.6Ce0.4Cu2O10 (R = Gd, Eu, and Sm) Magnetosuperconductors

“…Intensive research has been carried out to understand these magnetosuperconductors, particularly the Ru-1212 [3][4][5][6][7]. Ru-1212 displays a Curie transition at = 132 K and bulk superconductivity below 0-46 K depending on the sample preparations [3,7]. Superconductivity appears to be associated with the CuO 2 planes [6] with some types of long-range magnetic order that involves the RuO 2 planes [4].…”