Dresden 2020 – scientific programme

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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: Talk

Wednesday, March 18, 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 [1]. 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 [2] and rectification at current-voltage non-linearities [3]. Here, a new technique based on the Tien-Gordon equation [4] 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.

[1] S. Baumann et al.: Science 350 (6259), 417 (2015)

[2] C. Grosse et al.: Appl. Phys. Lett. 103, 183108 (2013)

[3] W. Paul et al.: Rev. Sci. Instrum. 87, 074703 (2016)

[4] G. Falci, V. Bubanja, G. Schön: Z. Phys. B 85, 451 (1991)