论文标题
电荷转移激发，配对密度波和Moiré材料中的超导性
Charge Transfer Excitations, Pair Density Waves, and Superconductivity in Moiré Materials
论文作者
论文摘要
过渡金属二北元化（TMD）双层是一类新的可调式摩尔系统，吸引了在二维中强烈相互交互的电子的量子模拟器引起的兴趣。特别是，最近的理论预测，在Half填充时观察到的相关绝缘子在WSE $ _2 $ _2 $/ws $ _2 $中观察到的是一种类似于Cuprates的电荷转移绝缘子，并且在进一步的孔掺杂时，在MoiréItialCell中不同位置的阳离子状孔子样中的电荷转移到了电荷转移到阳离子状的Orbitals。在这项工作中，我们证明在这种掺杂的电荷转移绝缘子中，紧密结合的电荷2E激发可以降低总静电排斥。这种复合激发，我们将其配置为三聚体，由与电荷转移激子结合的一对孔组成。当掺杂孔的带宽很小时，三聚体将以一系列相称的掺杂水平结晶成绝缘的配对密度波。当带宽与配对结合能相当时，巡回孔和电荷-2E三聚体会互动相互作用，从而导致非常规的超导性与Feshbach谐振附近的超速费米气体中的超流量相似。我们的理论广泛适用于强烈相互关联的电荷转移绝缘子，例如WSE $ _2 $/ws $ _2 $或在应用电场下的TMD同型。
Transition metal dichalcogenide (TMD) bilayers are a new class of tunable moiré systems attracting interest as quantum simulators of strongly-interacting electrons in two dimensions. In particular, recent theory predicts that the correlated insulator observed in WSe$_2$/WS$_2$ at half filling is a charge-transfer insulator similar to cuprates and, upon further hole doping, exhibits a transfer of charge from anion-like to cation-like orbitals at different locations in the moiré unit cell. In this work, we demonstrate that in this doped charge-transfer insulator, tightly-bound charge-2e excitations can form to lower the total electrostatic repulsion. This composite excitation, which we dub a trimer, consists of a pair of holes bound to a charge-transfer exciton. When the bandwidth of doped holes is small, trimers crystallize into insulating pair density waves at a sequence of commensurate doping levels. When the bandwidth becomes comparable to the pair binding energy, itinerant holes and charge-2e trimers interact resonantly, leading to unconventional superconductivity similar to superfluidity in an ultracold Fermi gas near Feshbach resonance. Our theory is broadly applicable to strongly-interacting charge-transfer insulators, such as WSe$_2$/WS$_2$ or TMD homobilayers under an applied electric field.
