Regensburg 2019 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 50: Plasmonics & Nanooptics III: STM and Time-Resolved Methods (joint session O/CPP)
O 50.4: Vortrag
Mittwoch, 3. April 2019, 11:15–11:30, H8
Simulating ultrashort light pulses in STM tunnel junctions — •Alexander Neef1, Dominik Peller2, Rupert Huber2, and Jascha Repp2 — 1Fritz-Haber-Institute of the MPG, D-14195, Berlin,Germany — 2Fakultaet fuer Physik, Universitaet Regensburg, D-93040 Regensburg, Germany
Combining ultrafast lightwave control and scanning tunneling miscroscopy (STM) recently opened the door to atomic-scale femtosecond imaging [1,2]. In lightwave STM, a THz field transient is coupled into the tunneling junction to apply an ultrashort bias voltage. The near-field waveform at the tip apex controls single-electron tunneling with combined femtosecond temporal and sub-Å spatial precision. Exploiting this process, single-molecule THz vibrations could be resolved directly in space and time [2]. The mechanism of sub-cycle tunneling control crucially depends on the exact shape of the near-field waveform in the junction, which is determined by interactions of the incoupled terahertz pulses with tip and substrate. To understand the effect of these near-field interactions on the voltage pulses in the junction, we carried out finite element simulations in the frequency domain. The resulting near-field waveforms coincide with experimental results. To further optimize the near-field transients, we study different geometries of the junction.
[1] T. L. Cocker et al., Nature Photon. 7, 620-625 (2013)
[2] T. L. Cocker, D. Peller, P. Yu, J. Repp, and R. Huber,
Nature 539, 263 (2016).