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Distinguished Lecture (general) - Dr. Sophie Guéron

Professor Sophie Guéron from the Laboratoire de Physique des solides in Orsay, France will visit California State University Long Beach to offer two special talks. All are welcome to attend.

Technical Lecture:
March 25. 11:00am in PH1-223.

General Lecture:
March 27. 10:00am in HSCI-100.

Abstract

Probing topological protection of Bismuth nanowire hinge states.

Bismuth has very recently been shown to belong to the family of Higher Order Topological Insulators, i.e. topological materials with insulating bulk and surfaces, but with metallic 1D "hinges" at the junction of its surfaces. I will show how we detected such hinge states in monocrystalline nanowires connected to superconducting contacts, and further used the supercurrent-versus-phase relation to demonstrate their ballistic nature. I will also present our recent measurement of the nanowire's linear response to an ac phase difference excitation. I will argue that the response's sharp dissipation peak when the superconducting phase difference is pi points to a topological protection of the Andreev levels carrying the super-current at the hinges.

Figure above: Bismuth nanowire (in brown) connected to superconducting electrodes (in blue), including a nanoconstriction and a loop geometry enabling the supercurrent-versus-phase relation measurement, as well as the ac susceptibility measurement probing the topological protection of the hinge states.