近日，美国加州大学圣巴巴拉分校的Chenhao Jin研究小组与亚利桑那州立大学的Sefaattin Tongay等人合作并取得一项新进展。经过不懈努力，他们发现了WSe₂/WS₂莫尔超晶格中激子的相关绝缘体。相关研究成果已于2023年5月11日在国际权威学术期刊《科学》上发表。

该研究团队观察到了由紧密束缚的电子空穴对，即激子组成的玻色子相关绝缘体，在WSe₂/WS₂莫尔超晶格中。他们开发了一种泵浦探测光谱方法，可以在激子填充量为ν_ex=1且电中性的情况下观察到激子不可压缩态，这表明形成了激子相关的绝缘体。当电荷密度变化时，这个玻色子相关的绝缘体会连续地过渡到电子相关绝缘体，在电子填充量为ν_e=1时，这表明存在两个极限之间的混合相关绝缘态。该研究表明，半导体莫尔超晶格是一个有趣的平台，可用于工程化玻色子相。

据悉，近期研究发现，在莫尔超晶格中观察到了各种非传统电子态。然而，对于类似的玻色子相的工程化，却仍然很少有探索。

附：英文原文

Title: Correlated insulator of excitons in WSe₂/WS₂ moiré superlattices

Author: Richen Xiong, Jacob H. Nie, Samuel L. Brantly, Patrick Hays, Renee Sailus, Kenji Watanabe, Takashi Taniguchi, Sefaattin Tongay, Chenhao Jin

Issue&Volume: 2023-05-11

Abstract: A panoply of unconventional electronic states has been observed in moiré superlattices. Engineering similar bosonic phases remains, however, largely unexplored. We report the observation of a bosonic correlated insulator in WSe₂/WS₂ moiré superlattices composed of excitons, i.e., tightly bound electron-hole pairs. We develop a pump probe spectroscopy method that we use to observe an exciton incompressible state at exciton filling ν_ex = 1 and charge neutrality, indicating a correlated insulator of excitons. With varying charge density, the bosonic correlated insulator continuously transitions into an electron correlated insulator at charge filling ν_e = 1, suggesting a mixed correlated insulating state between the two limits. Our studies establish semiconducting moiré superlattices as an intriguing platform for engineering bosonic phases.

DOI: add5574

Source: https://www.science.org/doi/10.1126/science.add5574