Tuning moiré excitons and correlated electronic states through layer degree of freedom

Dongxue Chen; Zhen Lian; Xiong Huang; Ying Su; Mina Rashetnia; Li Yan; Mark Blei; Takashi Taniguchi; Kenji Watanabe; Sefaattin Tongay; Zenghui Wang; Chuanwei Zhang; Yong-Tao Cui; Su-Fei Shi

doi:10.1038/s41467-022-32493-9

Tuning moiré excitons and correlated electronic states through layer degree of freedom

Nat Commun. 2022 Aug 16;13(1):4810. doi: 10.1038/s41467-022-32493-9.

Authors

Dongxue Chen^#^{1

2}, Zhen Lian^#², Xiong Huang^#^{3

4}, Ying Su^#⁵, Mina Rashetnia³, Li Yan², Mark Blei⁶, Takashi Taniguchi⁷, Kenji Watanabe⁸, Sefaattin Tongay⁶, Zenghui Wang⁹, Chuanwei Zhang¹⁰, Yong-Tao Cui¹¹, Su-Fei Shi^{12

13}

Affiliations

¹ Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu, Sichuan, China.
² Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, NY, 12180, USA.
³ Department of Physics and Astronomy, University of California, Riverside, CA, 92521, USA.
⁴ Department of Materials Science and Engineering, University of California, Riverside, CA, 92521, USA.
⁵ Department of Physics, University of Texas at Dallas, Dallas, TX, 75083, USA.
⁶ School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ, 85287, USA.
⁷ International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan.
⁸ Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan.
⁹ Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu, Sichuan, China. zenghui.wang@uestc.edu.cn.
¹⁰ Department of Physics, University of Texas at Dallas, Dallas, TX, 75083, USA. Chuanwei.Zhang@utdallas.edu.
¹¹ Department of Physics and Astronomy, University of California, Riverside, CA, 92521, USA. yongtao.cui@ucr.edu.
¹² Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, NY, 12180, USA. shis2@rpi.edu.
¹³ Department of Electrical, Computer & Systems Engineering, Rensselaer Polytechnic Institute, Troy, NY, 12180, USA. shis2@rpi.edu.

^# Contributed equally.

Abstract

Moiré coupling in transition metal dichalcogenides (TMDCs) superlattices introduces flat minibands that enable strong electronic correlation and fascinating correlated states, and it also modifies the strong Coulomb-interaction-driven excitons and gives rise to moiré excitons. Here, we introduce the layer degree of freedom to the WSe₂/WS₂ moiré superlattice by changing WSe₂ from monolayer to bilayer and trilayer. We observe systematic changes of optical spectra of the moiré excitons, which directly confirm the highly interfacial nature of moiré coupling at the WSe₂/WS₂ interface. In addition, the energy resonances of moiré excitons are strongly modified, with their separation significantly increased in multilayer WSe₂/monolayer WS₂ moiré superlattice. The additional WSe₂ layers also modulate the strong electronic correlation strength, evidenced by the reduced Mott transition temperature with added WSe₂ layer(s). The layer dependence of both moiré excitons and correlated electronic states can be well described by our theoretical model. Our study presents a new method to tune the strong electronic correlation and moiré exciton bands in the TMDCs moiré superlattices, ushering in an exciting platform to engineer quantum phenomena stemming from strong correlation and Coulomb interaction.

Abstract

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