1. Suppression of thermal smearing in a feedback-driven atomic size Josephson junction
- Author
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Escribano, Samuel D., Barrena, Víctor, Perconte, David, Moreno, Jose Antonio, Lomana, Marta Fernández, Águeda, Miguel, Herrera, Edwin, Wu, Beilun, Rodrigo, Jose Gabriel, Prada, Elsa, Guillamón, Isabel, Yeyati, Alfredo Levy, and Suderow, Hermann
- Subjects
Condensed Matter - Superconductivity - Abstract
The ultimate spatial limit to establish a Josephson coupling between two superconducting electrodes is an atomic-scale junction. The Josephson effect in such ultrasmall junctions has been used to unveil new switching dynamics, study coupling close to superconducting bound states or unveil non-reciprocal effects. However, coupling is weak and thermal smearing reduces the Cooper pair current magnitude. Here we show that a feedback element induces a time-dependent bistable regime which consists of periodic oscillations between two different Cooper pair tunneling states (corresponding to the DC and AC Josephson regimes respectively). The amplitude of the time-averaged current within the bistable regime is robust against thermal smearing. By tracing the periodic oscillations in the new bistable regime as a function of the position in a Scanning Tunneling Microscope (STM), we obtain atomic scale map of the critical current in 2H-NbSe$_2$ and find spatial modulations due to a pair density wave. Our results fundamentally improve our understanding of atomic size Josephson junctions and provide a promising new route to study superconducting materials through atomic scale maps of the Josephson coupling., Comment: 51 pages, 14 figures
- Published
- 2023