Proximity‐Effect‐Induced Superconductivity in Nb/Sb2Te3‐Nanoribbon/Nb Junctions

• Published in: Annalen der Physik 2020-08, Vol.532 (8), p.n/a
• Main Authors: Zhang, Jinzhong, Jalil, Abdur Rehman, Tse, Pok‐Lam, Kölzer, Jonas, Rosenbach, Daniel, Valencia, Helen, Luysberg, Martina, Mikulics, Martin, Panaitov, Gregory, Grützmacher, Detlev, Hu, Zhigao, Lu, Jia Grace, Schäpers, Thomas
• Format: Article
• Language: English
• Subjects: Antimony; Antimony telluride; Bias; Critical current (superconductivity); Electrodes; Electron beam lithography; Magnetic fields; Magnetic properties; Magnetron sputtering; Nanoribbons; Proximity; proximity effect; Sb2Te3 nanoribbons; Superconductivity; Superconductors; topological insulators; Transport properties
• ISSN: 0003-3804; 1521-3889
• DOI: 10.1002/andp.202000273

Nanohybrid superconducting junctions using antimony telluride (Sb2Te3) topological insulator nanoribbons and Nb superconducting electrodes are fabricated using electron beam lithography and magnetron sputtering. The effects of bias current, temperature, and magnetic field on the transport properties of the junctions in a four‐terminal measurement configuration are investigated. Two features are observed. First, the formation of a Josephson weak‐link junction. The junction is formed by proximity‐induced areas in the nanoribbon right underneath the inner Nb electrodes which are connected by the few tens of nanometers short Sb2Te3 bridge. At 0.5 K a critical current of 0.15 µA is observed. The decrease of the supercurrent with temperature is explained in the framework of a diffusive junction. Furthermore, the Josephson supercurrent is found to decrease monotonously with the magnetic field indicating that the structure is in the small‐junction limit. As a second feature, a transition is also observed in the differential resistance at larger bias currents and larger magnetic fields, which is attributed to the suppression of the proximity‐induced superconductive state in the nanoribbon area underneath the Nb electrodes. The transport properties of hybrid superconducting junctions based on antimony telluride topological insulator nanoribbons contacted with niobium superconducting electrodes are investigated. A clear Josephson supercurrent is observed, which decreases monotonously when a magnetic field is applied. Furthermore, indications of a proximity induced superconductive state are found in the nanoribbon area underneath the niobium electrodes.