期刊
NANO LETTERS
卷 20, 期 3, 页码 1959-1966出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.nanolett.9b05242
关键词
Lieb lattice; electronic topology; metal-phthalocyanine; metal-organic framework; first-principles calculations
类别
资金
- U.S. DOE-BES [DEFG02-04ER46148]
- SMART, one of seven centers of nCORE, a Semiconductor Research Corporation program - National Institute of Standards and Technology (NIST)
- NSFC [11774196, 11774325, 21603210]
- National Key Research and Development Program of China [2017YFA0204904]
- Fundamental Research Funds for the Central Universities
- MSI of University of Minnesota
- CHPC at University of Utah
Topological properties of the Lieb lattice, i.e., the edge-centered square lattice, have been extensively studied and are, however, mostly based on theoretical models without identifying real material systems. Here, based on tight-binding and first-principles calculations, we demonstrate the Lieb-lattice features of the experimentally synthesized phthalocyanine-based metal-organic framework (MPc-MOF), which holds various intriguing topological phase transitions through band engineering. First, we show that the MPc-MOFs indeed have a peculiar Lieb band structure with 1/3 filling, which has been overlooked because of its unconventional band structure deviating from the ideal Lieb band. The intrinsic MPc-MOF presents a trivial insulating state, with its gap size determined by the on-site energy difference (Delta E) between the corner and edge-center sites. Through either chemical substitution or physical strain engineering, one can tune Delta E to close the gap and achieve a topological phase transition. Specifically, upon closing the gap, topological semimetallic/insulating states emerge from nonmagnetic MPc-MOFs, while magnetic semimetal/Chern insulator states arise from magnetic MPc-MOFs, respectively. Our discovery greatly enriches our understanding of the Lieb lattice and provides a guideline for experimental observation of the Lieb-lattice-based topological states.
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