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Title: A nanoscale gigahertz source realized with Josephson scanning tunneling microscopy

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 25 GHz to 200 GHz and that large photon flux in excess of 10{sup 20 }cm{sup −2} s{sup −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.
Authors:
; ; ; ;  [1] ;  [2] ;  [1] ;  [3]
  1. Max-Planck-Institut für Festkörperforschung, 70569 Stuttgart (Germany)
  2. Institut für Theoretische Elektrotechnik, Technische Universität Hamburg-Harburg, 21079 Hamburg (Germany)
  3. (Switzerland)
Publication Date:
OSTI Identifier:
22395670
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 106; Journal Issue: 1; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ANTENNAS; COOPER PAIRS; ELECTRIC CONTACTS; EXCITATION; FREQUENCY DEPENDENCE; GHZ RANGE; IMPEDANCE; JOSEPHSON EFFECT; JOSEPHSON JUNCTIONS; NANOSTRUCTURES; PHOTON EMISSION; PHOTONS; SCANNING TUNNELING MICROSCOPY; SHORT WAVE RADIATION; SUPERCONDUCTORS; TUNNEL EFFECT; VANADIUM