Phonon-assisted Casimir interactions between piezoelectric materials

Abstract

The strong coupling between electromagnetic fields and lattice oscillations in piezoelectric materials gives rise to phonon polariton excitations. Such quasiparticles are important in modulating the ubiquitous Casimir force. Here by utilizing the generalized Born-Huang hydrodynamics model exemplified in SiC, three types of phonons are studied: longitudinal optical phonon, transverse optical phonon and phonon polariton. The Fresnel reflection coefficients for the piezoelectric composed of semi-infinite substrates or thin films are then obtained by taking into account the phonon-electromagnetic coupling. The Casimir interaction, calculated via a generalized Lifshitz approach, is examined to highlight the interplay between different types of phonon modes and electromagnetic excitations. Our study shows that piezoelectrics emerge as materials where this ubiquitous force can be controlled via phonon properties. Different types of surface phonon polaritons associated with structural polytypes may also be distinguished through the Casimir interaction.