Global phase diagram of twisted bilayer graphene above T<sub>C</sub>
ORAL
Abstract
We investigate the full doping and strain-dependent phase diagram (absent superconductivity) of magic-angle twisted bilayer graphene. Using comprehensive Hartree-Fock calculations, we show that at temperatures where superconductivity is absent the global phase structure can be understood based on the competition and coexistence between three types of intertwined orders: a fully symmetric phase, spatially uniform flavor-symmetry-breaking states, and an incommensurate Kekulé spiral (IKS) order. For small strain, the IKS phase, recently proposed as a candidate order at all non-zero integer fillings of the moiré unit cell, is found to be ubiquitous for non-integer doping as well. We demonstrate that the corresponding electronic compressibility and Fermi surface structure are consistent with the 'cascade' physics and Landau fans observed experimentally.
*NB is supported by a senior postdoctoral research fellowship of the Flanders Research Foundation (FWO). We acknowledge support from the European Research Council under the European Union Horizon 2020 Research and Innovation Programme, Grant Agreement No. 804213-TMCS and from EPSRC Grant EP/S020527/1.
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Publication: arXiv preprint arXiv:2109.09749
Presenters
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Glenn Wagner
- Univ of Zurich