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arXiv · 2109.09749

Global Phase Diagram of the Normal State of Twisted Bilayer Graphene

Glenn Wagner·Yves H. Kwan·Nick Bultinck·Steven H. Simon·S. A. Parameswaran
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Abstract

We investigate the full doping and strain-dependent phase diagram of the normal state of magic-angle twisted bilayer graphene (TBG). 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 Kekul\'e spiral (IKS) order. For small strain, the IKS phase, recently proposed as a candidate order at all non-zero integer fillings of the moir\'e 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. This suggests a unified picture of the phase diagram of TBG in terms of IKS order.

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Glenn Wagner, Yves H. Kwan, Nick Bultinck, Steven H. Simon, S. A. Parameswaran. 2021-09-20. Global Phase Diagram of the Normal State of Twisted Bilayer Graphene. https://doi.org/10.1103/physrevlett.128.156401

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