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Séminaire « Confinement et systèmes 2D » de l’INSP

Ballistic edge states in Bismuth nanowires revealed by SQUID interferometry - Anil Murani - Mardi 13 février 2018 à 11 h

INSP - Sorbonne Université - 4 place Jussieu - 75005 Paris - Barre 22-32, 2e étage, salle 201

Anil Murani, post-doctorant au Laboratoire de Physique des Solides à Orsay dans le groupe d’Hélène Bouchiat et Sophie Guéron.


The protection against backscattering provided by topology is a striking property. In two-dimensional insulators, a consequence of this topological protection is the ballistic nature of the one-dimensional helical edge states. One demonstration of ballisticity is the quantized Hall conductance. Here we provide another demonstration of ballistic transport, in the way the edge states carry a supercurrent. The system we have investigated is a micrometer-long monocrystalline bismuth nanowire with topological surfaces [1], that we connect to two superconducting electrodes. We have measured the relation between the Josephson current flowing through the nanowire and the superconducting phase difference at its ends, the current–phase relation. The sharp sawtooth-shaped phase-modulated current–phase relation we find demonstrates that transport occurs selectively along two ballistic edges of the nanowire [2]. I will also present a recent experiment that aims to answer quantitatively about the topological protection against backscattering as well as the lifetime of the metastable Andreev bound states that can be formed in these topological SNS junction [3, 4].

[1] S. Murakami, Phys. Rev. Lett. 97, 2006
[2] A. Murani et. al., Nat. Comm, 2017
[3] A. Murani et. al., Phys. Rev. B 96, 2017
[4] A. Murani et. al., in preparation