Straintronics, which aims at the control of the electronic properties and functionalities of two dimensional materials by using the curved structures or mechanically induced stresses, is an emerging new trend of nanoscience. Among a variety of two dimensional materials, transition metal dichalcogenides have a lot of distinct poly types and quantum phases and are also know to withstand large strain up to 10% [1], thus offering an ideal material platform for straintronics research.

Here, we report straintronic control of the optical properties in 3R-MoS₂, which has a unique stacking sequence and resultant noncentrosymmetric structure in multilayer forms [2]. By applying the strain in 3R-MoS₂, symmetry can be further controlled, leading to the emergence of the in-plane polarization. In the presentation, we focus on the nonlinear optical response originating from this emergent in-plane polarization in strain-engineered 3R MoS₂.

[1] S. Bertolazzi, et al. ACS Nano 5, 9703-9709 (2011)

[2] R. Suzuki, et al. Nature. Nanotech. 9, 611-617 (2014)