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O: Fachverband Oberflächenphysik
O 72: Scanning Probe Techniques I: STM-ESR and Method Development (joint session O/CPP)
O 72.5: Vortrag
Mittwoch, 18. März 2020, 16:00–16:15, TRE Ma
Transfer Function Compensation for High Frequency Radiation into an STM Tunnel Junction — •Maximilian Uhl, Piotr Kot, Robert Drost, and Christian R. Ast — Max-Planck-Institut für Festkörperforschung, Stuttgart
Creating constant amplitude radiation of varying frequencies in the tunnel junction of a scanning tunneling microscope is an important condition for probing the interaction of matter and electromagnetic waves at the nanoscale, such as for electron paramagnetic resonance . The transfer function describes the transmission of an AC signal to the tunnel juntion and depends highly non-linearly on the frequency. A known transfer function can be compensated by a frequency dependent signal power. Reaching non-zero constant amplitudes at frequencies >40 GHz has remained a challenge. Our setup makes this possible for frequencies up to 90 GHz. So far, transfer functions have been measured by plasmonic light emission  and rectification at current-voltage non-linearities . Here, a new technique based on the Tien-Gordon equation  is demonstrated. It allows to probe even small AC voltages in the µV range, requiring only a single measurement point per frequency. For that, we use the coherence peak of a superconductor-insulator-superconductor junction. Generally, the technique can also be used with other peak types in the current-voltage derivative.
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