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Spatially dispersing Yu-Shiba-Rusinov states in the unconventional superconductor FeTe<sub>0.55</sub>Se<sub>0.45</sub>

ORAL

Abstract

By using scanning tunneling microscopy (STM) we find and characterize dispersive, energy symmetric in-gap states in the iron-based superconductor FeTe0.55Se0.45, a material that exhibits signatures of topological superconductivity, and Majorana bound states at vortex cores or at impurity locations. We use a superconducting STM tip for enhanced energy resolution, which enables us to show that impurity states can be tuned through the Fermi level with varying tip-sample distance. We find that the impurity state is of the Yu-Shiba-Rusinov (YSR) type, and argue that the energy shift is caused by the low superfluid density in FeTe0.55Se0.45, which allows the electric field of the tip to slightly penetrate the sample. We model the newly introduced tip-gating scenario within the single-impurity Anderson model and find good agreement to the experimental data.

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Presenters

  • Damianos Chatzopoulos

    Leiden University

Authors

  • Damianos Chatzopoulos

    Leiden University

  • Doohee Cho

    Physics, Yonsei University

  • Koen Bastiaans

    Leiden University

  • Gorm O Steffensen

    Niels Bohr Institute, University of Copenhagen, Center for Quantum Devices, Niels Bohr Institute,University of Copenhagen

  • Damian Bouwmeester

    Delft University of Technology

  • Alireza Akbari

    Max Planck POSTECH Center for Complex Phase Materials

  • Genda Gu

    Brookhaven National Laboratory, Brookhaven National Laboratories, Brookhaven national lab, Brookhaven National Labs, Condensed Matter Physics and Materials Science Department, Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, CMPMS, Brookhaven National Laboratory, Brookhaven National Lab, COndensed Matter Physics and Materials Science Department, Brookhaven National Laboratory

  • Jens Paaske

    Niels Bohr Institute, University of Copenhagen, QuTech and Kavli Institute of Nanoscience, Delft University of Technology

  • Brian M Andersen

    Niels Bohr Institute, University of Copenhagen, Niels Bohr Institute, University of Copenhagen

  • Milan P. Allan

    Leiden Institute of Physics, Leiden University, Leiden University, Huygens-Kamerlingh Onnes Laboratory, Leiden University