19-22 giugno 2019
Strand Hotel Terme Delfini
Europe/Rome timezone

Coherent effects in junctions based on p-wave superconductor

19 giu 2019, 17:00
30m
Strand Hotel Terme Delfini

Strand Hotel Terme Delfini

Ischia, Napoli
invited oral session 1

Speaker

Alexander Golubov (Moscow Institute of Physics and Technology, Dolgoprudny, Russia, and Faculty of Science and Technology, University of Twente, Enschede, The Netherlands)

Description

The famed p-wave superconductivity harbors a variety of exotic topological states. The practical ways for its implementing are being extensively discussed in literature, and the contact of a superconductor with the topological insulator is expected to become the most promising candidate. There have been reports of the 4π-periodicity in such contacts, which are a hallmark of the p-wave superconductivity. However, the phase-sensitive measurements of the Josephson currents that would serve as conclusive evidence of the p-wave symmetry are still lacking. In this work we report direct observation of the Josephson effect in the Nb/Bi2Te2Se/Nb structures which are characterized by ballistic electronic transport across the Bi2Te2Se nanocrystals. We show that in the mK temperature range the investigated junctions exhibit a new type of oscillations of the Josephson current in magnetic field with an ultra-short period ∼ 1 Oe corresponding to energy spectrum with the level spacing of order of 1 µeV. We develop theoretical model explaining these oscillations in terms of fine structure of low-energy Andreev bound states. The results are consistent with emerging p-wave superconducting correlations induced at the Bi2Te2Se surface due to an interplay between the s-wave superconductivity in Nb and a peculiar symmetry of the topological insulator Bi2Te2Se. This work is supported by the Russian Science Foundation (Project No. 18-72-10118), the EU H2020-WIDESPREAD-05-2017-Twinning project “SPINTECH” (the Grant Agreement No. 810144) and by Dutch FOM.

Primary authors

Dr. V.S. Stolyarov (Moscow Institute of Physics and Technology, Dolgoprudny, Russia) Mr. D.S. Yakovlev (Institute of Solid State Physics of the Russian Academy of Sciences, Chernogolovka, Russia) Ms. O.V. Skryabina (Institute of Solid State Physics of the Russian Academy of Sciences, Chernogolovka, Russia) Dr. V. Gurtovoy (Moscow Institute of Physics and Technology, Dolgoprudny, Russia) Mr. D.S. Lvov (Institute of Solid State Physics of the Russian Academy of Sciences, Chernogolovka, Russia) Dr. S.V. Egorov (Institute of Solid State Physics of the Russian Academy of Sciences, Chernogolovka, Russia) Prof. V.V. Ryazanov (Institute of Solid State Physics of the Russian Academy of Sciences, Chernogolovka, Russia) Prof. D. Roditchev ( Institut des Nanosciences de Paris, Sorbonne Université, CNRS, UMR7588, Paris, France) Dr. V.M. Vinokur (Argonne National Laboratory, USA) Alexander Golubov (Moscow Institute of Physics and Technology, Dolgoprudny, Russia, and Faculty of Science and Technology, University of Twente, Enschede, The Netherlands)

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