Proximity-induced superconductivity in (Bi${}_{1-x}$Sb${}_x$)${}_2$Te${}_3$ topological-insulator nanowires

Abstract

When a topological insulator is made into a nanowire, the interplay between topology and size quantization gives rise to peculiar one-dimensional states whose energy dispersion can be manipulated by external fields. In the presence of proximity-induced superconductivity, these 1D states offer a tunable platform for Majorana zero modes. While the existence of such peculiar 1D states has been experimentally confirmed, the realization of robust proximity-induced superconductivity in topological-insulator nanowires remains a challenge. Here, we report the realization of superconducting topological-insulator nanowires based on (Bi${}_{1-x}$Sb${}_x$)${}_2$Te${}_3$ (BST) thin films. When two rectangular pads of palladium are deposited on a BST thin film with a separation of 100--200 nm, the BST beneath the pads is converted into a superconductor, leaving a nanowire of BST in-between. We found that the interface is epitaxial and has a high electronic transparency, leading to a robust superconductivity induced in the BST nanowire. Due to its suitable geometry for gate-tuning, this platform is promising for future studies of Majorana zero modes.

33 pages total; 22 pages of main text with 4 figures, 11 pages of supplementary information with 8 figures. This version of the article has been accepted for publication, after peer review, but is not the Version of Record and does not reflect post-acceptance improvements, or any corrections

References in corpus (6)

• Superconducting proximity effect and Majorana fermions at the surface of a topological insulator
• Aharonov-Bohm oscillations in disordered topological insulator nanowires
• Anomalous Aharonov-Bohm conductance oscillations from topological insulator surface states
• Giant magnetochiral anisotropy from quantum confined surface states of topological insulator nanowires
• Majorana bound states in topological insulators without a vortex
• Gate-induced decoupling of surface and bulk state properties in selectively-deposited Bi${}_2$Te${}_3$ nanoribbons

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