Abstract
We present a method to identify distinct tunneling modes in a tunable superconducting tunnel junction composed of a superconducting tip and a sample in a scanning tunneling microscope. Combining the relative decay constant of tunneling current extracted from $I\ensuremath{-}V\ensuremath{-}z$ spectroscopy with its statistical analysis over the atomic disorders in the sample surface, we identified the crossover of dominant tunneling modes between single charge tunneling, Andreev reflection (AR), and Josephson tunneling with respect to the bias voltage at a measurement temperature nearly half of the critical temperature. The method enables one to determine the specific tunneling regime independently of the spectral shapes and to reveal intrinsic modulation of AR and Josephson current by disorder that will be crucial for superconducting quantum information processing.
Highlights
The tunnel junction between superconductors is the heart of modern quantum information devices
Our results indicate that the statistical analysis of I-V-z spectroscopy is a powerful method to distinguish various tunneling regimes with minimal assumption for the physical model and specific spectral shapes
The structure of dI/dV first rapidly decreases with approaching the Fermi level, and reveals an increase of tunneling conductance at the Fermi level, for spectra acquired with closest proximity between the tip and the surface
Summary
The tunnel junction between superconductors is the heart of modern quantum information devices. The previous studies mostly focused on the clean limit (absence of disorder) and the junction temperature much less than the critical temperature It is less explored how tunneling mechanisms and their crossover behave in the presence of disorder and finite temperature, which is crucial for both practical application of superconducting tunnel junctions and fundamental investigation of proximity of phase transitions. These regimes require the development of a robust method to distinguish between tunneling mechanisms that is complementary to detailed analysis of spectral shapes
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
