High transparency Bi2Se3 topological insulator nanoribbon Josephson junctions with low resistive noise properties

TL;DR

This paper reports the fabrication of high-quality, low-noise Josephson junctions using Bi2Se3 topological insulator nanoribbons with aluminum electrodes, demonstrating high transparency and stability suitable for topological superconductivity studies.

Contribution

The work introduces a catalyst-free PVD method to create highly transparent, low-noise Al/Bi2Se3 Josephson junctions with exceptional stability, advancing topological insulator device research.

Findings

High transparency of Al/Bi2Se3 interface confirmed by conductance spectra.

Low relative resistance noise below 1×10^{-12} μm^2/Hz.

Critical current and gap values close to aluminum's superconducting gap.

Abstract

Bi$_2$Se$_3$ nanoribbons, grown by catalyst-free Physical Vapour Deposition, have been used to fabricate high quality Josephson junctions with Al superconducting electrodes. The conductance spectra (dI/dV) of the junctions show clear dip-peak structures characteristic of multiple Andreev reflections. The temperature dependence of the dip-peak features reveals a highly transparent Al/Bi$_2$Se$_3$ topological insulator nanoribbon interface and Josephson junction barrier. This is supported by the high values of the Bi$_2$Se$_3$ induced gap and of I$_c$R$_n$ (I$_c$ critical current, R$_n$ normal resistance of the junction) product both of the order of 160 $\mu$eV, a value close to the Al gap. The devices present an extremely low relative resistance noise below 1$\times$10$^{-12}$ $\mu$m$^2$/Hz comparable to the best Al tunnel junctions, which indicates a high stability in the transmission coefficients of transport channels. The ideal Al/Bi$_2$Se$_3$ interface properties, perfect transparency for Cooper pair transport in conjunction with low resistive noise make these junctions a suitable platform for further studies of the induced topological superconductivity and Majorana bound states physics.