Hyperbolic phonon-plasmon polaritons in a hBN-graphene van der Waals structure
In this paper a thorough theoretical study of a new class of collective excitations, dubbed hyperbolic surface phonon plasmon polaritons, is performed. This new type of light-matter excitations are shown to have unique properties that allows to explore them both as the basis of ultra-sensitive devices to the dielectric nature of its surroundings. The system is a van der Waals heterostructure -- a layered metamaterial, composed of different 2D materials in direct contact one with another, namely graphene ribbons and hexagonal boron nitride slabs of nanometric size. In the paper we discuss the spectrum of these new class of excitations, the associated electromagnetic fields, the sensitivity to the dielectric function of its surroundings, and the absorption spectrum. All this is accomplished using an analytical model that considerably diminishes the computational burden, as well as elucidates the underling physical mechanism of the excitations supported by the device.