SKM 2023 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 87: Focus Session: Scanning Probe Microscopy with Quartz Sensors III

O 87.5: Topical Talk

Donnerstag, 30. März 2023, 16:15–16:45, TRE Ma

Application of atomic force microscopy with quartz sensors to quantum states in graphene and related twisted heterostructures — •Joseph Stroscio — National Institute of Standards and Technology, Gaithersburg, MD, USA.

Atomic force microscopy (AFM) with quartz sensors pioneered by Franz Giessibl has opened many applications in quantum nanoscience where AFM measurements can be made simultaneously and conveniently with scanning tunneling microscopy measurements (STM). In this presentation I will review our work using combined AFM/STM measurements to give a microscopic view of the quantum states in single layer graphene and in twisted graphene heterostructures. In single layer graphene, electrostatic pn junction boundaries provide a convenient geometry for the examination of quantum Hall edge states with microscopic probes. For a graphene Hall bar device defined and tunable by dual gates, we carry out simultaneous AFM, STM, and electrical transport measurements in the system which we developed for detailed measurements of two-dimensional devices in-operando at mK temperatures and in magnetic fields up to 15 T. The AFM, operated in the Kelvin probe force microscopy (KPFM) mode, detects the chemical potential transitions when Landau levels are being filled or emptied as a function of back gate potential with the same fidelity as the scanning tunneling spectroscopy measurements. With KPFM we can map the dispersion of the Landau levels across the quantum Hall edge boundary as a function of density and spatial position.