Giant enhancement of the axial Casimir force of a rotating particle near hyperbolic metasurface

We show that the axial Casimir force (ACF) acting on a rotating nanoparticle can also act in the proximity of a hyperbolic metasurface made of graphene ribbons since it was first demonstrated to exist near a bi-isotropic material. The ACF can be enhanced by several orders of magnitude compared with that in the bi-isotropic configuration. We numerically demonstrate that the largest ACF exerted on the particle can be achieved when the rotation direction of the nanoparticle is parallel to the hyperbolic metasurface. ACF is also determined by the azimuth angle between the rotating axis and the edge of the metasurface. The dependence of ACF on the chemical potential and ribbon width of graphene is also investigated in detail. ACF increases as the chemical potential increases for fixed ribbon width. For given chemical potential, ACF increases first and then decreases after reaching the maximum value when the ribbon width increases. The results extend the application of hyperbolic metasurfaces in regulating Casimir interactions.