Hung Nguyen Tuan, Zhang Kunyan, Van Thanh Vuong, Guo Yunfan, Puretzky Alexander A, Geohegan David B, Kong Jing, Huang Shengxi, Saito Riichiro
Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Sendai 980-8578, Japan.
Department of Physics, Tohoku University, Sendai 980-8578, Japan.
ACS Nano. 2023 Oct 24;17(20):19877-19886. doi: 10.1021/acsnano.3c04436. Epub 2023 Aug 29.
Nonlinear optical responses in second harmonic generation (SHG) of van der Waals heterobilayers, Janus MoSSe/MoS, 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, 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/MoS 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 point group symmetry of the MoSSe/MoS, enhances calculated χ values for both AA (900 pm/V) and AB (300 pm/V) stackings 1.6 times as large as that without strain.
通过在第一性原理计算中采用交换关联混合泛函和实时方法，理论上优化了范德华异质双层Janus MoSSe/MoS在二次谐波产生（SHG）中的非线性光学响应，该响应是应变和堆叠顺序的函数。我们发现，由于AA堆叠中反演对称性的破坏，AA堆叠（550 pm/V）中计算出的非线性极化率χ比AB堆叠（170 pm/V）大三倍。将目前的理论预测与Janus MoSSe/MoS异质双层的观测SHG光谱进行比较，其中AA堆叠的峰值SHG强度是AB堆叠的四倍。此外，一个相对较大的二维应变（4%）破坏了MoSSe/MoS的点群对称性，增强了AA（900 pm/V）和AB（300 pm/V）堆叠的计算χ值，比无应变时大1.6倍。
