Quantum interferences in bismuth nanowires based Josephson junctions: signature of topological ballistic edge states?

CFM Seminars

Speaker

Helen Bouchiat (Laboratoire de Physique des Solides, Université Paris Sud)

When

2016/04/08
14:00

Place

Donostia International Physics Center (DIPC)

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"Quantum interferences in bismuth nanowires based Josephson junctions: signature of topological ballistic edge states?" Anil Murani, Alik Kasumov, Sophie Guéron, Richard Deblock and Hélène Bouchiat LPS, CNRS Univ. Paris Sud, Université Paris Saclay 91405 Orsay We investigate proximity induced superconductivity in micrometer-long single crystal bismuth nanowires connected to superconducting electrodes with a high critical field. At low temperature we measure a supercurrent that persists in magnetic fields as high as the critical field of the electrodes. The critical current is also strongly modulated by the magnetic field. In certain samples we find regular, rapid periodic oscillations occurring up to high fields. Other samples exhibit less periodic but full modulations of the critical current on Tesla field scales, with field-caused extinctions of the supercurrent. These findings indicate the existence of low dimensionally, phase coherent, interfering conducting regions through the samples. We relate these results to the electronic properties of the (111) surface states of bismuth with strong Rashba spin-orbit coupling. In particular recent experiments in SQUID geometry reveal the contribution of ballistic edge states along the nanowires.