Wagner Glenn, Kwan Yves H, Bultinck Nick, Simon Steven H, Parameswaran S A
Rudolf Peierls Centre for Theoretical Physics, Parks Road, Oxford OX1 3PU, United Kingdom.
Department of Physics, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland.
Phys Rev Lett. 2022 Apr 15;128(15):156401. doi: 10.1103/PhysRevLett.128.156401.
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 Kekulé spiral (IKS) order. For small strain, the IKS phase, recently proposed as a candidate order at all nonzero integer fillings of the moiré unit cell, is found to be ubiquitous for noninteger 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.
我们研究了魔角扭曲双层石墨烯(TBG)正常态的全掺杂和应变依赖相图。通过全面的哈特里 - 福克计算,我们表明,在不存在超导性的温度下,基于三种相互交织的有序态之间的竞争和共存,可以理解全局相结构:一个完全对称相、空间均匀的味对称性破缺态以及一个非公度的凯库勒螺旋(IKS)序。对于小应变,最近被提议作为莫尔晶胞所有非零整数填充时的候选有序态的IKS相,被发现对于非整数掺杂也是普遍存在的。我们证明,相应的电子压缩性和费米面结构与实验观察到的“级联”物理和朗道扇一致。这表明了基于IKS序的TBG相图的统一图景。