Classical Casimir-Polder force between polarizable microparticles and thin films including graphene

摘要

We derive analytic expressions for the classical Casimir-Polder free energyand force for a polarizable (magnetizable) atom (microparticle) interactingwith thin films, made of different materials, or graphene. It is shown that foran isolated dielectric film the free energy and force decrease quicker withseparation, as compared to the case of atom interacting with a thick plate(semispace). For metallic films some peculiar features depending on the modelof a metal used are analyzed. For an atom interacting with graphene wedemonstrate that at room temperature the classical regime is achieved at about$1.5\,\mu$m separation. In this regime the contributions to the free energy andforce due to atomic magnetic polarizability are suppressed, as compared to mainterms caused by the atomic electric polarizability. According to our results,at separations above $5\,\mu$m the Casimir-Polder interaction of atoms withgraphene is of the same strength as with an ideal-metal plane. The classicalinteraction of atoms with thin films deposited on substrates is alsoconsidered.