Hyperbolicity in two-dimensional transition metal ditellurides induced by electronic bands nesting

Naturally occurring hyperbolic plasmonic media is rare, and was only recently observed in the 1T′ phase of WTe2. We elucidate on the physical origin of this strong infrared hyperbolic response, and attribute it to band-nested anisotropic interband transitions. Such a phenomenon does not occur in general anisotropic materials, at least not in their pristine state. However, band-nested anisotropic interband transitions can in principle be induced via proper electronic band nesting. We illustrate this principle and demonstrate a topological elliptic-to-hyperbolic transition in MoTe2 via strain engineering, which is otherwise nonhyperbolic.