Monolayer transition-metal dichalcogenides (TMDCs) display valley-selective circular dichroismdue to the presence of time-reversal symmetry and the absence of inversion symmetry, making thempromising candidates for valleytronics. In contrast, in bilayer TMDCs both symmetries are present andthese desirable valley-selective properties are lost. Here, by using density-functional tight-bindingelectronic structure simulations and revised periodic boundary conditions, we show that bending ofbilayer MoS2 sheets breaks band degeneracies and localizes states on separate layers due to bendinginducedstrain gradients across the sheets. We propose a strategy for employing bending deformations inbilayer TMDCs as a simple yet effective means of dynamically and reversibly tuning their band gapswhile simultaneously tuning valley-selective physics.
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