Accessing Non-equilibrium States at Atomic Scales

Event Type: IFIMAColloquium.
Title: Accessing Non-equilibrium States at Atomic Scales
When: Friday, 06th October, 2023, at 12:00.
Where: Sala de Grados, Building C, Escuela Politécnica Superior, Universidad Autónoma de Madrid.
Speaker: Jascha Repp, Department of Physics, University of Regensburg, 93040 Regensburg, Germany.

Scanning probe microscopy (SPM) has revolutionized our understanding of the atomistic world. Conventional SPM, however, is an inherently slow technique – too slow to capture transition states in excitation processes in most cases. While studying ultra-fast non-equilibrium phenomena is enabled by terahertz (THz) scanning tunneling microscopy (STM) [Nature 539, 263 (2016)], another approach gives us access to intermediate timescales that are relevant for spin precession and relaxations. We introduce a novel variant of SPM by combining principles of STM and atomic force microscopy (AFM). This enables operation in absence of any conductance of the underlying substrate, while retaining the capability of imaging electronic states with sub-angstrom resolution. Thereby, we can access out-of-equilibrium charge states that are out of reach for conventional STM [Nature 566, 245 (2019)]. Extending this technique by electronic pump-probe spectroscopy, we measured the triplet lifetime of an individual pentacene molecule on an insulating surface [Science 373, 452 (2021)] and lifetime quenching by nearby oxygen molecules. Combined with radio-frequency magnetic-field driving we introduce AFM-based electron spin resonance and spin manipulation showing long spin coherence in single molecules [arXiv:2212.12244 (2022)].

Accessing Non-equilibrium States at Atomic Scales - Poster

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