Berlin 2024 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 54: Scanning Probe Microscopy: Light Matter Interaction at Atomic Scales I

O 54.6: Topical Talk

Mittwoch, 20. März 2024, 16:30–17:00, MA 041

Ultrafast scanning tunnelling spectroscopy of a phonon-driven atomic vacancy in a monolayer crystal — Carmen Roelcke, Lukas Kastner, Maximilian Graml, Andreas Biereder, Jan Wilhelm, Jascha Repp, Rupert Huber, and •Yaroslav Gerasimenko — Department of Physics and Regensburg Center for Ultrafast Nanoscopy (RUN), University of Regensburg, 93040 Regensburg, Germany

Directly observing in actual microscopic videography how the motion of a specific atom affects the electronic structure and the functionality of solids has been a long-held dream of modern science. Here, we break this ground with tomographic lightwave-driven scanning tunnelling spectroscopy by taking snapshots of the electronic spectrum of a phonon-driven atomic defect faster than the vibration period. We directly resolve in space, time, and energy how atomic motion transiently modulates the bound state of a selenium vacancy, the archetypal single-photon emitter, in a WSe₂ monolayer. By combining atomically-confined excitation of a drum-like phonon with ultrafast tunnelling spectroscopy reaching atomic spatial and 300 fs temporal resolution, we reveal transient energy shifts of the lowest bound defect state by up to 40 meV, depending on the amplitude and phase of the phonon. This combination marks a disruptive development towards understanding and control of quantum matter by accessing key mechanisms at their intrinsic length, time and energy scales.

Keywords: ultrafast nanoscopy; lightwave-driven scanning tunnelling spectroscopy; 2D semiconductors; electron-phonon coupling; single-photon emitters