Exciton-Exciton Interactions in Van der Waals Heterobilayers,Physical Review X

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Exciton-Exciton Interactions in Van der Waals Heterobilayers
Physical Review X ( IF 11.6 ) Pub Date : 2024-08-14 , DOI: 10.1103/physrevx.14.031025
Alexander Steinhoff _{1,

1} , Edith Wietek ₂ , Matthias Florian ₃ , Tommy Schulz _{1,

1} , Takashi Taniguchi ₄ , Kenji Watanabe ₄ , Shen Zhao ₅ , Alexander Högele _{5,

6} , Frank Jahnke _{1,

1} , Alexey Chernikov ₂

Affiliation

Exciton-exciton interactions are key to understanding nonlinear optical and transport phenomena in van der Waals heterobilayers, which emerged as versatile platforms to study correlated electronic states. We present a combined theory-experiment study of excitonic many-body effects based on first-principle band structures and Coulomb interaction matrix elements. Key to our approach is the explicit treatment of the fermionic substructure of excitons and dynamical screening effects for density-induced energy renormalization and dissipation. We demonstrate that dipolar blueshifts are almost perfectly compensated by many-body effects, mainly by screening-induced self-energy corrections. Moreover, we identify a crossover between attractive and repulsive behavior at elevated exciton densities. Theoretical findings are supported by experimental studies of spectrally narrow, mobile interlayer excitons in atomically reconstructed, h-BN-encapsulated MoSe2/WSe2 heterobilayers. Both theory and experiment show energy renormalization on a scale of a few meV even for high injection densities in the vicinity of the Mott transition. Our results revise the established picture of dipolar repulsion dominating exciton-exciton interactions in van der Waals heterostructures and open up opportunities for their external design.

Published by the American Physical Society

2024

中文翻译：

范德华异质双层中的激子-激子相互作用

激子-激子相互作用是理解范德华异质层中非线性光学和传输现象的关键，范德华异质层成为研究相关电子态的多功能平台。我们提出了基于第一性原理能带结构和库仑相互作用矩阵元件的激子多体效应的理论-实验研究。我们方法的关键是明确处理激子的费米子子结构和密度诱导能量重整化和耗散的动力学筛选效应。我们证明偶极蓝移几乎完全被多体效应补偿，主要是通过筛选诱导的自我能量校正。此外，我们确定了在高激子密度下吸引行为和排斥行为之间的交叉。原子重构、h-BN 封装的 MoSe2/WSe2 异质双层中光谱狭窄的移动层间激子的实验研究支持了理论发现。理论和实验都表明，即使在莫特跃迁附近的高注入密度下，能量重整化也在几 meV 的尺度上。我们的结果修正了偶极排斥在范德华异质结构中支配激子-激子相互作用的既定图景，并为它们的外部设计开辟了机会。美国物理学会 2024 年出版

更新日期：2024-08-14

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