Charge localization and reentrant superconductivity in a quasi-ballistic InAs nanowire coupled to superconductors

• Published in: Science advances 2019-07, Vol.5 (7), p.eaav1235-eaav1235
• Main Authors: Estrada Saldaña, J C, Žitko, R, Cleuziou, J P, Lee, E J H, Zannier, V, Ercolani, D, Sorba, L, Aguado, R, De Franceschi, S
• Format: Article
• Language: English
• Subjects: Condensed Matter Physics; Physics; SciAdv r-articles
• ISSN: 2375-2548; 2375-2548
• DOI: 10.1126/sciadv.aav1235

A semiconductor nanowire with strong spin-orbit coupling in proximity to a superconductor is predicted to display Majorana edge states emerging under a properly oriented magnetic field. The experimental investigation of these exotic states requires assessing the one-dimensional (1D) character of the nanowire and understanding the superconducting proximity effect in the presence of a magnetic field. Here, we explore the quasi-ballistic 1D transport regime of an InAs nanowire with Ta contacts. Fine-tuned by means of local gates, the observed plateaus of approximately quantized conductance hide the presence of a localized electron, giving rise to a lurking Coulomb blockade effect and Kondo physics. When Ta becomes superconducting, this local charge causes an unusual, reentrant magnetic field dependence of the supercurrent, which we ascribe to a 0 - π transition. Our results underline the relevant role of unintentional charge localization in the few-channel regime where helical subbands and Majorana quasi-particles are expected to arise.