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arXiv 2104.08352cond-mat.mes-hall
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均质双层半导体莫尔超晶格中偶极谷激子的发光异常

Luminescence anomaly of dipolar valley excitons in homobilayer semiconductor moiré superlattices

Hongyi Yu, Wang Yao

摘要:

在扭曲的同质双层过渡金属二硫属化物中,层内和层间谷激子与在莫尔条纹中空间变化的层配置杂交。基态谷激子被捕获在具有相反电偶极子的两个高对称点处的莫尔超晶胞中,形成最近邻偶极吸引的蜂窝超晶格。我们发现,层配置的空间纹理的结果在莫尔陷阱激子的发光异常,其中微小的位移的相互作用显着增加亮度和改变偏振从圆形到线性。在完全填充时,辐射复合主要发生在激子超晶格的边缘和空位处。这种异常也表现在小星系团的级联发射中,产生了偏振纠缠光子链。层间偏置可以将超晶格转换为仅具有排斥相互作用的单轨道三角晶格,其中发光异常可以用来区分分数填充时的有序状态和畴边界。

英文摘要:

In twisted homobilayer transition metal dichalcogenides, intra- and inter-layer valley excitons hybridize with the layer configurations spatially varying in the moiré. The ground state valley excitons are trapped at two high-symmetry points with opposite electric dipoles in a moiré supercell, forming a honeycomb superlattice of nearest-neighbor dipolar attraction. We find that the spatial texture of layer configuration results in a luminescence anomaly of the moiré trapped excitons, where a tiny displacement by interactions dramatically increases the brightness and changes polarization from circular to linear. At full filling, radiative recombination predominantly occurs at edges and vacancies of the exciton superlattice. The anomaly also manifests in the cascaded emission of small clusters, producing chains of polarization entangled photons. An interlayer bias can switch the superlattice into a single-orbital triangular lattice with repulsive interactions only, where the luminescence anomaly can be exploited to distinguish ordered states and domain boundaries at fractional filling.

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