期刊
SOLID STATE COMMUNICATIONS
卷 282, 期 -, 页码 38-44出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.ssc.2018.07.013
关键词
-
资金
- Singapore Ministry of Education [MOE2017-T2-1-130, MOE2017-T2-2-140]
Using the continuum model for low energy non-interacting electronic structure of moire van der Waals heterostructures developed by Bistritzer and MacDonald [1], we study the competition between spin, charge, and superconducting order in twisted bilayer graphene. Surprisingly, we find that for a range of small angles inclusive of the so-called magic angle, this model features robust Fermi pockets that preclude any Mott insulating phase at weak coupling. However, a Fermi surface reconstruction at theta greater than or similar to 1.2 degrees gives emergent van Hove singularities without any Fermi pockets. Using a hot-spot model for Fermi surface patches around these emergent saddle points, we develop a random-phase approximation from which we obtain a phase diagram very similar to that obtained recently by Isobe, Yuan, and Fu using the parquet renormalization group [2] but with additional insights. For example, our model shows strong nesting around time-reversal symmetric points at a moderate doping of similar to 2 x 10(11) cm(-2) away from the van Hove singularity. When this nesting dominates, we predict that charge-order enhances singlet superconductivity, while spin-order suppresses superconductivity. Our theory also provides additional possibilities for the case of unnested Fermi surfaces.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据