Proximity-induced superconductivity in (Bi1−xSbx)2Te3 topological-insulator nanowires
Mengmeng Bai, Xian‐Kui Wei, Junya Feng, M. Luysberg, Andrea Bliesener, Gertjan Lippertz, Anjana Uday, A. A. Taskin, Joachim Mayer, Yoichi Ando
Abstract
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.