Induced unconventional superconductivity on the surface states of Bi2Te3 topological insulator

• Published in: Nature Communications
• Main Authors: Charpentier, Sophie, galletti, luca, Kunakova, Gunta, Arpaia, Riccardo, Song, Yuxin, Baghdadi, Reza, Wang, Shu Min, Kalaboukhov, Alexei, Olsson, Eva, Tafuri, Francesco, Golubev, Dmitry, Linder, Jacob, Bauch, Thilo, Lombardi, Floriana
• Language: unknown
• Published: 2017
• Subjects: Physical Sciences; Condensed Matter Physics; bi2se3; symmetry; strain; edge; junctions; thin-films; IPY
• Online Access: https://doi.org/10.1038/s41467-017-02069-z; https://research.chalmers.se/en/publication/254131

Topological superconductivity is central to a variety of novel phenomena involving the interplay between topologically ordered phases and broken-symmetry states. The key ingredient is an unconventional order parameter, with an orbital component containing a chiral p(x) + ip(y) wave term. Here we present phase-sensitive measurements, based on the quantum interference in nanoscale Josephson junctions, realized by using Bi2Te3 topological insulator. We demonstrate that the induced superconductivity is unconventional and consistent with a sign-changing order parameter, such as a chiral px + ipy component. The magnetic field pattern of the junctions shows a dip at zero externally applied magnetic field, which is an incontrovertible signature of the simultaneous existence of 0 and pi coupling within the junction, inherent to a non trivial order parameter phase. The nano-textured morphology of the Bi2Te3 flakes, and the dramatic role played by thermal strain are the surprising key factors for the display of an unconventional induced order parameter.