Wystąpienie ustne Marcin Kisiel (WCN-Czw)
Energy dissipation on twisted bilayer graphene at magic angle twist
University of Basel, Department of Physics,, Klingelbergstrasse 242, 4056 Basel, Switzerland
Understanding nanoscale energy dissipation is nowadays among few priorities particularly in quantum systems. Whilst 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 (5 K) nanomechanical energy dissipation of tBLG measured by sharp tip of the pendulum atomic force microscope (pAFM). Ultrasensitive cantilever tip acting as oscillating plunger gate over the quantum device showed giant dissipation peaks attributed to different fractional filling of the flat energy bands. Dissipation spectroscopy allows to determine the twist angle distribution of tBLG. Thus, nanomechanical 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. Application of magnetic fields provoked strong oscillations of the force and dissipation signal which is strongly enhanced for fractional 3/4 band filling.