Proximity-induced odd-frequency superconductivity in a topological insulator

Journal article

At an interface between a topological insulator (TI) and a conventional superconductor (SC), superconductivity has been predicted to change dramatically and exhibit novel correlations. In particular, the induced superconductivity by an s-wave SC in a TI can develop an order parameter with a p-wave component. Here we present experimental evidence for an unexpected proximity-induced novel superconducting state in a thin layer of the prototypical TI, Bi2Se3 proximity coupled to Nb. From depthresolved magnetic field measurements below the superconducting transition temperature of Nb, we observe a local enhancement of the magnetic field in Bi2Se3 that exceeds the externally applied field, thus supporting the existence of an intrinsic paramagnetic Meissner effect arising from an odd-frequency superconducting state. Our experimental results are complemented by theoretical calculations supporting the appearance of such a component at the interface which extends into the TI. This state is topologically distinct from the conventional Bardeen-Cooper-Schrieffer state it originates from. To the best of our knowledge, these findings present a first observation of bulk odd-frequency superconductivity in a TI. We thus reaffirm the potential of the TI-SC interface as a versatile platform to produce novel superconducting states.

Authors: Krieger, JA; Pertsova, A; Giblin, SR; Döbeli, M; Prokscha, T

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Physical Society
• Journal: Physical Review Letters
• Volume: 125
• Issue: 2
• Article number: 026802
• Publication date: 2020-07-10
• Acceptance date: 2020-06-16
• DOI: 10.1103/PhysRevLett.125.026802
• EISSN: 1079-7114
• ISSN: 0031-9007
• Language: English
• Keywords: FFR