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 Blonder–Tinkham–Klapwijk model considering a d-wave symmetry of the superconducting order parameter. Remarkably low values of the energy gap Δ=(2.8±0.2) meV and of the 2Δ∕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 Δ vs H evolution, a critical magnetic field Hc2≃30 T 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.
Pairing state in the ruthenocuprate superconductor RuSr2GdCu2O8: A point-contact Andreev reflection spectroscopy study
BOBBA, Fabrizio;CUCOLO, Anna Maria;
2006
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 Blonder–Tinkham–Klapwijk model considering a d-wave symmetry of the superconducting order parameter. Remarkably low values of the energy gap Δ=(2.8±0.2) meV and of the 2Δ∕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 Δ vs H evolution, a critical magnetic field Hc2≃30 T 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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
