Journal
PHYSICAL REVIEW B
Volume 88, Issue 8, Pages -Publisher
AMER PHYSICAL SOC
DOI: 10.1103/PhysRevB.88.085433
Keywords
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Funding
- HKSAR Research Grant Council [HKU706412P]
- Croucher Foundation under the Croucher Innovation Award
- National Basic Research Program of China 973 Program [2013CB934500, 2011CBA00100]
- Basic Research Funds of Beijing Institute of Technology [20121842003]
- National Natural Science Foundation of China [11225418, 11174337]
- Specialized Research Fund for the Doctoral Program of Higher Education of China [20121101110046]
- U.S. Department of Energy, Office of Basic Energy Sciences, Materials Sciences and Engineering Division
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We present a three-band tight-binding (TB) model for describing the low-energy physics in monolayers of group-VIB transition metal dichalcogenides MX2 (M = Mo, W; X = S, Se, Te). As the conduction- and valence-band edges are predominantly contributed by the d(z2), d(xy), and d(x2-y2) orbitals of M atoms, the TB model is constructed using these three orbitals based on the symmetries of the monolayers. Parameters of the TB model are fitted from the first-principles energy bands for all MX2 monolayers. The TB model involving only the nearest-neighbor M-M hoppings is sufficient to capture the band-edge properties in the +/-K valleys, including the energy dispersions as well as the Berry curvatures. The TB model involving up to the third-nearest-neighbor M-M hoppings can well reproduce the energy bands in the entire Brillouin zone. Spin-orbit coupling in valence bands is well accounted for by including the on-site spin-orbit interactions of M atoms. The conduction band also exhibits a small valley-dependent spin splitting which has an overall sign difference between MoX2 and WX2. We discuss the origins of these corrections to the three-band model. The three-band TB model developed here is efficient to account for low-energy physics in MX2 monolayers, and its simplicity can be particularly useful in the study of many-body physics and physics of edge states.
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