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Signatures of Topological Superconductivity in Bulk-Insulating Topological Insulator BiSbTe1.25Se1.75 in Proximity with Superconducting NbSe2

Banerjee, Abhishek and Sundaresh, Ananthesh and Ganesan, Rajamanickam and Kumar, PS Anil (2018) Signatures of Topological Superconductivity in Bulk-Insulating Topological Insulator BiSbTe1.25Se1.75 in Proximity with Superconducting NbSe2. In: ACS NANO, 12 (12). pp. 12665-12672.

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Official URL: https://doi.org/10.1103/10.1021/acsnano.8b07550

Abstract

The combination of superconductivity and spin-momentum locking at the interface between an s-wave superconductor and a three-dimensional topological insulator (3D-TI) is predicted to generate exotic p-wave topological superconducting phases that can host Majorana Fermions. However, large bulk conductivities of previously investigated 3D-TI samples and Fermi level mismatches between 3D bulk superconductors and 2D topological surface states have thwarted significant progress. Here, we employ bulk-insulating topological insulators in proximity with two-dimensional superconductor NbSe2 assembled via van der Waals epitaxy. Experimentally measured differential conductance yields unusual features including a double-gap spectrum, an intrinsic asymmetry that vanishes with small in-plane magnetic fields, differential conductance ripples at biases significantly larger than the superconducting gap. We explain our results on the basis of proximity-induced superconductivity of topological surface states, while also considering possibilities of topologically trivial superconductivity arising from Rashba-type surface states. Our work demonstrates the possibility of obtaining p-wave superconductors by proximity effects on bulk-insulating TIs.

Item Type: Journal Article
Additional Information: Copyright of this article belongs to AMER CHEMICAL SOC
Keywords: topological superconductivity; Majorana Fermions; proximity effect; topological insulator; 2D superconductor; van der Waals heterostructure
Department/Centre: Division of Physical & Mathematical Sciences > Physics
Depositing User: Id for Latest eprints
Date Deposited: 28 Jan 2019 09:27
Last Modified: 28 Jan 2019 09:27
URI: http://eprints.iisc.ac.in/id/eprint/61491

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