Low frequency noise in ballistic Nb/Ag point contacts

Jian Wei; Goutam Sheet; Venkat Chandrasekhar

doi:10.1063/1.3479927

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arXiv · 1004.5451

Low frequency noise in ballistic Nb/Ag point contacts

Jian Wei·Goutam Sheet·Venkat Chandrasekhar

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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.

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Jian Wei, Goutam Sheet, Venkat Chandrasekhar. 2010-04-30. Low frequency noise in ballistic Nb/Ag point contacts. https://doi.org/10.1063/1.3479927

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