Strain Tuning of the Anisotropy in the Optoelectronic Properties of TiS₃

The benefits of two-dimensional (2D) materials for applications in nanotechnology can be widened by exploiting the intrinsic anisotropy of some of those crystals, being black phosphorus the most well-known example. In this work we demonstrate that the anisotropy of TiS₃, which is even stronger than that of black phosphorus, can be tuned by means of strain engineering. Using density functional theory calculations, we find that the ellipticity of the valence band can be inverted under moderate compressive strain, which is accompanied by an enhancement of the optical absorption. It is shown that the strain tuning of the band anisotropy can be exploited to focus plasmons in the desired direction, a feature that could be used to design TiS₃ nanostructures with switchable plasmon channeling.