Natural hyperbolic two-dimensional systems are a fascinating class of materials that could open alternative pathways to manipulating plasmon propagation and light-matter interactions. Here, we present a comprehensive study of the optical response in Td -WTe2 by means of density-functional and many-body perturbation theories. We show how monolayer WTe2 with in-plane anisotropy sustains hyperbolic plasmon polaritons, which can be tuned via chemical doping and strain. The latter is able to extend the hyperbolic regime toward the near-infrared with low losses. Moreover, WTe2 can even be switched between elliptic and hyperbolic regimes with a moderate strain. In addition, plasmons in WTe2 are characterized by low losses owing to electron-phonon scattering, which is responsible for the temperature dependence of the plasmon line width. Interestingly, the temperature can also be utilized to tune the in-plane anisotropy of the WTe2 optical response.
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