Gate-controlled superconductivity in diffusive multiwalled carbon nanotube

TL;DR

This study demonstrates gate-tunable proximity-induced superconductivity in diffusive multiwalled carbon nanotubes with measurable critical currents and phase diffusion effects, advancing understanding of superconducting transport in nanoscale systems.

Contribution

It provides the first detailed analysis of gate-controlled superconductivity in diffusive multiwalled carbon nanotubes, applying the long, diffusive Josephson junction model.

Findings

Critical current up to 1.3 nA, tunable by gate voltage.

Zero bias resistance varies with critical current as R_0 ∝ I_cm^-0.74.

Good agreement with long, diffusive Josephson junction theory.

Abstract

We have investigated electrical transport in a diffusive multiwalled carbon nanotube contacted using superconducting leads made of Al/Ti sandwich structure. We find proximity-induced superconductivity with measured critical currents up to I_cm = 1.3 nA, tunable by gate voltage down to 10 pA. The supercurrent branch displays a finite zero bias resistance which varies as R_0 proportional to I_cm^-alpha with alpha=0.74. Using IV-characteristics of junctions with phase diffusion, a good agreement is obtained with Josephson coupling energy in the long, diffusive junction model of A.D Zaikin and G.F. Zharkov (Sov. J. Low Temp. Phys. 7, 184 (1981)).