Modulation of the Casimir force via graphene plasmons-SiC surface phonon polaritons coupling

Abstract

The Casimir force is a macroscopic quantum effect arising from quantum vacuum fluctuations, playing a dominant role in the interactions between microstructures at the nanoscale. However, due to its relatively weak magnitude, the precise measurement of this force still faces significant challenges. Therefore, optimizing material selection and structural design to enhance and manipulate this effect has become a key direction in related research. This study systematically investigates the modulation mechanism of the Casimir force in graphene–silicon carbide (SiC) composite structure. The research indicates that, at a separation distance of d = 10 nm, the Casimir force is dominated by the ultraviolet range, while its modulation is primarily determined by the infrared (IR) range. Compared to the single SiC structure, the force spectrum of the composite structure in the IR region shows that, below 1.53 × 1014 rad/s, the attractive force originates from graphene surface plasmon polaritons (SPPs); above this frequency, the attractive force arises from coupling between graphene SPPs and SiC surface phonon polaritons (SPhPs). By adjusting the Fermi level of graphene, its electrical conductivity can be tuned, thereby modifying the frequency response range of the SPPs and further controlling the coupling between SPPs and SPhPs, as well as the amplitude of the Casimir force. This study provides important theoretical foundations for precision measurement of Casimir forces and anti-stiction structural design in micro/nano-electromechanical systems.