论文标题
Moiré系统中的Van Hove奇异性促进的配对密度波和循环电流
Pair density wave and loop current promoted by van Hove singularities in moiré systems
论文作者
论文摘要
从理论上讲，我们表明，在存在常规或更高阶段的Van Hove奇点（VHS）的情况下，裸露的动量配对（也称为PDW），易感性可以促进到每种valley-Contrux 3 $ flux $ flux $ flux $ flux $ frol pla $ nian triangull pla pla $ bcs的相同顺序中$ ϕ = \fracπ{6} $在Moiré系统中。这使得PDW顺序成为具有排斥相互作用的电子系统的潜在不稳定。我们确认，它确实赢得了所有其他不稳定性的胜利，并通过重新归一化组的计算和通量插入论点在某些条件下成为基态。此外，我们还发现，如果带有常规VHS的费米表面完美地嵌套在$ ϕ = \fracπ{3} $的情况下，拓扑非平凡的环路电流序列将成为领先的不稳定性。与Haldane模型相似，该循环电流状态具有量子异常效果。如果我们加入此循环当前状态或引入有限的下一个邻居跳，跳上$ t^{\ prime} $，手性$ d $ -wave pdw将成为主要的不稳定。在实验上，可以通过基于石墨烯和过渡金属二核苷的Moiré系统中的平面外电场有效调节通量。
We theoretically show that in the presence of conventional or higher order van Hove singularities(VHS), the bare finite momentum pairing, also known as the pair density wave (PDW), susceptibility can be promoted to the same order of the most divergent bare BCS susceptibility through a valley-contrasting flux 3$ϕ$ in each triangular plaquette at $ϕ=\fracπ{3}$ and $ϕ=\fracπ{6}$ in moiré systems. This makes the PDW order a possible leading instability for an electronic system with repulsive interactions. We confirm that it indeed wins over all other instabilities and becomes the ground state under certain conditions through the renormalization group calculation and a flux insertion argument. Moreover, we also find that a topological nontrivial loop current order becomes the leading instability if the Fermi surface with conventional VHS is perfectly nested at $ϕ=\fracπ{3}$. Similar to the Haldane model, this loop current state has the quantum anomalous Hall effect. If we dope this loop current state or introduce a finite next-nearest neighbour hopping $t^{\prime}$, the chiral $d$-wave PDW becomes the dominant instability. Experimentally, the flux can be effectively tuned by an out-of-plane electric field in moiré systems based on graphene and transition metal dichalcogenides.
