近日，美国加州大学的L. V.Butov及其研究团队取得一项新进展。经过不懈努力，他们揭示范德华异质结构中间接激子的输运和局域化过程。相关研究成果已于2024年6月18日在国际知名学术期刊《自然—光子学》上发表。

在MoSe₂/WSe₂异质结构中，该研究团队实现了IX（层间激子）的长程输运，其1/e衰减距离达到或超过了100μm。然而，这种长程输运在温度约10K以上时会消失。随着IX密度的增加，研究人员观察到了IX的局域化现象，随后又出现了IX的长程输运和再次局域化。IX输运对密度的依赖关系并非单调，这一特性与玻色-哈伯德理论中关于莫尔维尔超晶格周期势中的超流体和绝缘相的预测相吻合。

据悉，长寿期的空间间接激子(IXs)，也被称为层间激子，允许实现量子激子系统和长程激子输运。由过渡金属二硫族化合物原子薄层组成的范德华异质结构为探索摩尔超晶格中的IXs提供了机会。人们对过渡金属二硫化物异质结构中的IX输运进行了深入研究，实现了1/e衰减距离达约4μm的IX扩散输运。

附:英文原文

Title: Transport and localization of indirect excitons in a van der Waals heterostructure

Author: Fowler-Gerace, L. H., Zhou, Zhiwen, Szwed, E. A., Choksy, D. J., Butov, L. V.

Issue&Volume: 2024-06-18

Abstract: Long lifetimes of spatially indirect excitons (IXs), also known as interlayer excitons, allow implementing both quantum exciton systems and long-range exciton transport. The van der Waals heterostructures composed of atomically thin layers of transition-metal dichalcogenides offer the opportunity to explore IXs in moiré superlattices. IX transport in transition-metal dichalcogenide heterostructures was intensively studied and diffusive IX transport with 1/e decay distances up to ~4μm was realized. Here, in a MoSe₂/WSe₂ heterostructure, we present the IX long-range transport with 1/e decay distances reaching and exceeding 100μm. The IX long-range transport vanishes at temperatures above ~10K. With increasing IX density, IX localization followed by IX long-range transport and IX re-entrant localization are observed. The non-monotonic dependence of IX transport on density is in qualitative agreement with the Bose–Hubbard theory prediction for superfluid and insulating phases in periodic potentials of moiré superlattices.

DOI: 10.1038/s41566-024-01435-w

Source: https://www.nature.com/articles/s41566-024-01435-w