Novel ways of probing heavy quasiparticles and cascades in magic angle twisted bilayer graphene

Magic Angle Twisted Bilayer Graphene (TBG) features very flat energy bands near the Fermi level, making it highly susceptible to the effect of electronic interactions. This leads to a plethora of correlated phenomena that depend on doping, temperature, and magnetic fields. One of the most notable effects is the cascades, a series of asymmetric resets in the Scanning Tunneling Spectrum and inverse compressibility of TBG around integer fillings. These cascades remain stable up to tens of Kelvin, making them some of the most resilient correlated phenomena observed in TBG.

Using Dynamical Mean Field Calculations, we recently showed that these cascades can be explained by the formation of heavy quasiparticles and local moments in the normal state [1], without the need for symmetry breaking, which only occurs at much lower temperatures (around a few Kelvin). This description can account for the resistive states (conductivity drops) near integer fillings, observable also up to high temperatures. I will discuss new ways to probe these cascade phenomena, including optical measurements and the Quantum Twisting Microscope, as well as the unconventional temperature dependence of the electronic properties.

[1] Heavy quasiparticles and cascades without symmetry breaking in twisted bilayer graphene. Anushree Datta, M.J. Calderón, A. Camjayi, E. Bascones. Nature Communications 14, 5036 (2023).