Academic Affiliation: Institute for Functional Matter and Quantum Technologies, University of Stuttgart, Germany

Talk: February 26, 2019

State-of-the-art in ultrafast scanning tunneling microscopy

Combining the advantages of ultrafast laser spectroscopy and atomic-resolution scanning probe microscopy into one tool has been a dream for quite some time. Technological progress in picosecond electronics and reliable laser sources has now turned this dream into reality. Two methods appear particularly promising: all-electronic excitation and optical excitation by THz light.
All-electronic excitation offers a versatile platform in which radio frequency sources or arbitrary waveform generators can be used to study time domain dynamics such as spin relaxation or even frequency-domain information such as spin resonance. THz pump-probe spectroscopy, on the other hand, circumvents any bandwidth limits of cabling and directly excited the STM’s tunnel junction enabling time resolution of approximately 100 fs. Both techniques utilize the non-linearity of the tunneling current to down-convert the fast measurements into quasi-DC signals that are detectable in the STM. I will review recent progress of these techniques, the physics underlying the excitation and detection mechanism and applications to spins on surfaces.