Mott phase in a van der Waals transition-metal halide at single layer limit

Two-dimensional materials offer opportunities for unravelling unprecedented ordered states at single layer limit. Among such ordered states, Mott phase is rarely explored. Here, we report the Mott phase in van der Waals chromium (II) iodide (CrI2) films. High quality CrI2 films with atomically flat...

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Published inarXiv.org
Main Authors Lang, Peng, Zhao, Jianzhou, Gui-Yuan, Hua, Min-Cai, Hui-Nan Xia, Yuan, Yuan, Wen-Hao, Zhang, Xu, Gang, Ling-Xiao, Zhao, Zeng-Wei, Zhu, Xiang, Tao, Ying-Shuang Fu
Format Paper Journal Article
LanguageEnglish
Published Ithaca Cornell University Library, arXiv.org 09.12.2019
Subjects
Chromium
Correlation analysis
Electron states
Epitaxial growth
Ferromagnetism
Flat surfaces
Graphitization
Low temperature
Mean field theory
Metal halides
Molecular beam epitaxy
Physics - Materials Science
Physics - Mesoscale and Nanoscale Physics
Substrates
Transition metals
Two dimensional materials
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Summary:Two-dimensional materials offer opportunities for unravelling unprecedented ordered states at single layer limit. Among such ordered states, Mott phase is rarely explored. Here, we report the Mott phase in van der Waals chromium (II) iodide (CrI2) films. High quality CrI2 films with atomically flat surface and macro size are grown on graphitized 6H-SiC(0001) substrate by molecular beam epitaxy. By in situ low temperature scanning tunneling microscopy and spectroscopy (STM/STS), we reveal that the film has a band gap as large as ~3.2 eV, which is nearly thickness independent. Density functional plus dynamic mean field theory calculations suggest that CrI2 films may be a strong Mott insulator with a ferromagnetically ordered ground state. The Mott phase is corroborated by the spectral band splitting, that is consistent with the extended Hubbard model, and gap reduction at charge dopants. Our study provides a platform for studying correlated electron states at single layer limit.
ISSN:2331-8422
DOI:10.48550/arxiv.1912.04069