Abstract
Nonlinear optical responses in second harmonic generation (SHG) of van der Waals heterobilayers, Janus MoSSe/MoS2, are theoretically optimized as a function of strain and stacking order by adopting an exchange-correlation hybrid functional and a real-time approach in first-principles calculation. We find that the calculated nonlinear susceptibility, χ(2), in AA stacking (550 pm/V) becomes three times as large as AB stacking (170 pm/V) due to the broken inversion symmetry in the AA stacking. The present theoretical prediction is compared with the observed SHG spectra of Janus MoSSe/MoS2 heterobilayers, in which the peak SHG intensity of AA stacking becomes four times as large as AB stacking. Furthermore, a relatively large, two-dimensional strain (4%) that breaks the C3v point group symmetry of the MoSSe/MoS2, enhances calculated χ(2) values for both AA (900 pm/V) and AB (300 pm/V) stackings 1.6 times as large as that without strain.
Original language | English |
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Pages (from-to) | 19877-19886 |
Number of pages | 10 |
Journal | ACS Nano |
Volume | 17 |
Issue number | 20 |
DOIs | |
State | Published - Oct 24 2023 |
Funding
N.T.H. acknowledges financial support from the Frontier Research Institute for Interdisciplinary Sciences, Tohoku University. R.S. acknowledges JSPS Kakenhi No. JP22H00283. K.Z. and S.H. acknowledge National Science Foundation (Grant Nos. ECCS-2246564 and ECCS-1943895). S.H. also acknowledges funding from the Air Force Office of Scientific Research (AFOSR) under Grant No. FA9550-22-1-0408. Y.G. and J.K. acknowledge the financial support from U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences under Award No. DE-SC0020042. The SHG measurements were supported by the Center for Nanophase Materials Sciences (CNMS), which is a U.S. Department of Energy, Office of Science User Facility at Oak Ridge National Laboratory.
Keywords
- 2D Janus heterobilayers
- first-principles calculations
- second-harmonic generation
- stacking effect
- strain engineering
- time-dependent density-functional theory