Carbon nanotube Josephson junctions with Nb contacts

Carbon nanotube Josephson junctions with Nb contacts

We report on the preparation of carbon nanotube Josephson junctions using superconducting electrodes made of niobium. Gate-controllable supercurrents with values of up to 30 nA are induced by the proximity effect. The IV curves are hysteretic at low temperature and the corresponding switching histograms have a width of 0.5%–2%. An on-chip resistive environment integrated in the sample layout is...

Multiwall Carbon Nanotube Josephson Junctions with Niobium Contacts

Self-shunted Nb/AlOx/Nb Josephson junctions

We describe the fabrication and properties of high critical current density (Jc) Nb/AlOx/Nb Josephson junctions with deep-submicron dimensions. The junctions are fabricated using a planarized process in which all levels are patterned using a combination of optical and electron beam lithography. The base and counter electrodes are defined by reactive ion etching using quartz etch masks to give a...

Gate-tuned high frequency response of carbon nanotube Josephson junctions.

Carbon nanotube Josephson junctions in the open quantum dot limit are fabricated using Pd/Al bilayer electrodes, and exhibit gate-controlled superconducting switching currents. Shapiro voltage steps can be observed under radio frequency current excitations, with a damping of the phase dynamics that strongly depends on the gate voltage. These measurements are described by a standard resistively ...

0-π oscillations in nanostructured Nb/Fe/Nb Josephson junctions

The physics of the π phase shift in ferromagnetic Josephson junctions enables a range of applications for spin-electronic devices and quantum computing. We investigate transitions from “0” to “π” states in Nb/Fe/Nb Josephson junctions by varying the Fe barrier thickness from 0.5 nm to 5.5 nm. From magnetic measurements we estimate for Fe a magnetic dead layer of about 1.1 nm. By fitting the cha...