Dresden 2020 – scientific programme

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O: Fachverband Oberflächenphysik

O 72: Scanning Probe Techniques I: STM-ESR and Method Development (joint session O/CPP)

O 72.8: Talk

Wednesday, March 18, 2020, 16:45–17:00, TRE Ma

Fast quasiparticle interference mapping through traveling salesperson and sparse sampling optimization — •Jens Oppliger and Fabian D. Natterer — Department of Physics, University of Zurich, Switzerland

STM investigations are slow and render complex measurement tasks, such as QPI mapping, impractical. Conventionally, QPI patterns are composed from a Fourier-transform of hundreds of thousands of point-spectra that encode LDOS modulations from which the scattering space is inferred. Yet, despite this measurement complexity, we rely heavily on QPI since it provides insight into materials that are experimentally inaccessible to ARPES. Surprisingly, QPI patterns contain only little information, despite their origin from many data-points. Since sparsity is one key-ingredient for compressive sensing, we use it here to fundamentally speed-up QPI mapping [1]. In view of the incoherent measurements required for CS, we sparsely sample LDOS at randomly selected locations using constant and varying probability density. To that end, we move the STM-tip according to a traveling salesperson and ultimately achieve a 5-50 times faster QPI mapping. [1] J. Oppliger and F.D. Natterer, arXiv 1908.01903