A nanoscale gigahertz source realized with Josephson scanning tunneling microscopy

Journal
Applied physics letters  
Volume
106
Issue
1
Article Number
013109
Citation
Applied Physics Letters 106 (1): 013109 (2015-01-05)
Publisher DOI
10.1063/1.4905322
Scopus ID
2-s2.0-84923769234
Publisher
American Institut of Physics
Using the AC Josephson effect in the superconductor-vacuum-superconductor tunnel junction of a scanning tunneling microscope (STM), we demonstrate the generation of GHz radiation. With the macroscopic STM tip acting as a λ/4-monopole antenna, we first show that the atomic scale Josephson junction in the STM is sensitive to its frequency-dependent environmental impedance in the GHz regime. Further, enhancing Cooper pair tunneling via excitations of the tip eigenmodes, we are able to generate high-frequency radiation. We find that for vanadium junctions, the enhanced photon emission can be tuned from about 25GHz to 200GHz and that large photon flux in excess of 1020cm-2 s-1 is reached in the tunnel junction. These findings demonstrate that the atomic scale Josephson junction in an STM can be employed as a full spectroscopic tool for GHz frequencies on the atomic scale.
DDC Class
530: Physik
Funding Organisations
Deutsche Forschungsgemeinschaft (DFG)  
More Funding Information
Ast acknowledges funding from the Emmy-Noether-Program of the Deutsche Forschungsgemeinschaft (DFG).