Regensburg 2019 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 72: Poster Wednesday: Scanning Probe Techniques
O 72.2: Poster
Mittwoch, 3. April 2019, 17:45–20:00, Poster B2
Upgrade of a low-temperature STM for single atom electron spin resonance — •Fabian D. Natterer1,2, François Patthey1, Tobias Bilgeri1, Patrick R. Forrester1,2, Nicolas Weiss1, and Harald Brune1 — 1Institute of Physics, EPFL, Lausanne, Switzerland — 2Physik-Institut, University of Zurich, Switzerland
Electron spin resonance with a scanning tunneling microscope (ESR-STM) combines temperature independent energy resolution in the nano-electron range and control of the atomic dimensions. We describe here the transformation of a low-temperature STM to an ESR-STM. The system is capable of delivering RF power to the tunnel junction at frequencies up to 30 GHz. We perform ESR on the model system TiH/MgO/Ag(100) by sweeping the magnetic field and find a magnetic moment of (1.004 ± 0.001) µB . Our upgrade enables to toggle between a DC mode, where the STM is operated with the regular control electronics, and an ultrafast-pulsed mode that uses an arbitrary waveform generator for pump-probe spectroscopy or reading of spin-states. Both modes allow for simultaneous radiofrequency excitation, which we add via a resistive pick-off tee to the bias voltage path. The RF cabling from room temperature to the 350 mK stage has an average attenuation of 18 dB between 5 and 25 GHz. Additional losses occur at the flexible cable segment connecting the STM tip. We discuss our transmission losses and indicate ways to reduce attenuation. We finally demonstrate how to synchronize the arrival times of RF and DC pulses coming from different paths to the STM junction, a prerequisite for future pulsed ESR experiments.