Probing Proximity-Induced Superconductivity in InAs Nanowires Using Built-In Barriers

Elalaily, Tosson and Kürtössy, Olivér and Zannier, Valentina and Scherübl, Zoltán and Lukács, István Endre and Srivastava, Pawan and Rossi, Francesca and Sorba, Lucia and Csonka, Szabolcs and Makk, Péter (2020) Probing Proximity-Induced Superconductivity in InAs Nanowires Using Built-In Barriers. PHYSICAL REVIEW APPLIED, 14 (4). pp. 1-8. ISSN 2331-7019

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Abstract

Bound states in superconductor-nanowire hybrid devices play a central role, carrying information on ground-state properties (Shiba or Andreev states) or on the topological properties of the system (Majorana states). The spectroscopy of such bound states relies on the formation of well-defined tunnel barriers, usually defined by gate electrodes, which results in smooth tunnel barriers. Here we used thin InP segments embedded into InAs nanowire during the growth process to form a sharp built-in tunnel barrier. Gate dependence and thermal-activation measurements are used to confirm the presence and estimate the height of this barrier. By coupling these wires to superconducting electrodes we investigate the gate voltage dependence of the induced gap in the nanowire segment, which we can understand using a simple model based on Andreev bound states. Our results show that these built-in barriers are promising as future spectroscopic tools.

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