SKM 2023 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 93: Graphene II: Electronic Structure and Growth

O 93.1: Vortrag

Freitag, 31. März 2023, 10:30–10:45, GER 37

Energy dissipation on magic angle twisted bilayer graphene — •Marcin Kisiel, Alexina Ollier, Urs Gysin, and Ernst Meyer — Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland

Understanding nanoscale energy dissipation is nowadays among few priorities particularly in quantum systems. While traditional Joule dissipation omnipresent in today's electronic devices is well understood, the energy loss of the strongly interacting electron systems remains largely unexplored. Twisted bilayer graphene (tBLG) is a host of interaction-driven correlated insulating phases, when the relative rotation is close to the magic angle (1.08deg). Here, we report on low temperature (5K) nanomechanical energy dissipation of tBLG measured by sharp tip of the pendulum atomic force microscope (pAFM). Ultrasensitive cantilever tip acting as an oscillating gate over the quantum device shows dissipation peaks attributed to different fractional filling of the flat energy bands. pAFM provides exquisite spatial resolution and thus allows to determine the twist angle distribution of tBLG. Strikingly it does it without literally touching the sample surface. Application of magnetic fields provoked strong oscillations of the dissipation signal at 3/4 band filling, which we identified as familiar to Aharonov-Bohm oscillations. The work demonstrates that nano-mechanical energy dissipation provides a rich source of information on the dissipative nature of the correlated electronic system of tBLG, with implications for coupling a mechanical oscillator to the quantum devices.