Low frequency noise in ballistic Nb/Ag point contacts

Abstract

We report on the low frequency noise in the ballistic point-contacts between a silver tip and a niobium foil. The ballistic nature of the point-contacts is confirmed by Andreev reflection spectroscopy at low bias voltage with the Nb foil cooled below its superconducting transition temperature ($T_c$). We find that the voltage dependence of the low frequency noise differs for different point-contacts with varying contact resistances. At high bias voltages, random two level fluctuations appear and dominate over the background $1/f$ noise. From analysis of the Andreev reflection spectra, we show that such two level fluctuators may give rise to depairing of the superconducting order parameter.

4 pages, 4 figures

References in corpus (4)

• The BCS-like gap in superconductor SmFeAsO_0.85F_0.15
• Probing multiband superconductivity by point-contact spectroscopy
• The role of critical current on point contact Andreev Reflection spectrum between a normal metal and a superconductor
• Anomalous Noise in the Pseudogap Regime of YBa${}_2$Cu${}_3$O${}_{7-\delta }$

Cited by in corpus (5)

• High Frequency Nonlinear Response of Superconducting Cavity-Grade Nb surfaces
• Anatomy of point-contact Andreev reflection spectroscopy from the experimental point of view (review)
• Enhanced superconductivity at the interface of W/Sr${}_2$RuO${}_4$ point contact
• High transport spin polarization in the van der Waals ferromagnet Fe${}_4$GeTe${}_2$
• Zero-bias anomalies on Sr${}_{0.88}$La${}_{0.12}$CuO${}_2$ thin films