论文标题
Floquet分数Chern绝缘子和扭曲双层石墨烯的竞争阶段
Floquet Fractional Chern Insulators and Competing Phases in Twisted Bilayer Graphene
论文作者
论文摘要
当考虑到电子电子相互作用时，我们研究了扭曲的双层石墨烯中的多体物理学，并定期驱动圆形极化光。在高驾驶频率$ω$的限制下，我们使用Floquet理论通过截断为$ω^{ - 2} $的有效静态汉密尔顿式制定系统，该均由单电子部分和筛选的库仑交互。我们通过在扭曲角度和驾驶强度跨越的参数空间中进行广泛的对角度来模拟这种有效的哈密顿量。值得注意的是，在参数空间的广泛区域中，我们确定了部分填充的浮子价带中的浮标分数Chern绝缘子状态。我们通过基态变性，光谱流和纠缠光谱来表征这些拓扑排序的状态。在缺乏分数的参数空间区域中，我们发现拓扑琐碎的电荷密度波和带分散诱导的费米液体，这些液体与分数Chern绝缘子状态势力强烈。
We study the many-body physics in twisted bilayer graphene coupled to periodic driving of a circularly polarized light when electron-electron interactions are taken into account. In the limit of high driving frequency $Ω$, we use Floquet theory to formulate the system by an effective static Hamiltonian truncated to the order of $Ω^{-2}$, which consists of a single-electron part and the screened Coulomb interaction. We numerically simulate this effective Hamiltonian by extensive exact diagonalization in the parameter space spanned by the twist angle and the driving strength. Remarkably, in a wide region of the parameter space, we identify Floquet fractional Chern insulator states in the partially filled Floquet valence bands. We characterize these topologically ordered states by ground-state degeneracy, spectral flow, and entanglement spectrum. In regions of the parameter space where fractional Chern insulator states are absent, we find topologically trivial charge density waves and band-dispersion-induced Fermi liquids which strongly compete with fractional Chern insulator states.
