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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 12: Diamond and Related Dielectric Materials II

KFM 12.6: Vortrag

Mittwoch, 20. März 2024, 11:30–11:50, TC 010

Energy dissipation on magic angle twisted bilayer graphene — •Marcin Kisiel¹, Alexina Ollier¹, Urs Gysin¹, Martino Poggio¹, Xiaobo Lu², Dmitri Efetov³, and Ernst Meyer¹ — ¹Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland — ²International Center for Quantum Materials, Collaborative Innovation Center of Quantum Matter, Peking University, 100871, Beijing, China — ³Department of Physics, Ludwig-Maximilians-University München, Geschwister- Scholl-Platz 1, 80539 München, Germany

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. 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 arising from wavefunction interference present between domains of different doping.

Keywords: energy dissipation, twisted bilayer graphene