On the Axion Electrodynamics in a two-dimensional slab and the Casimir effect

We analyze the Axion Electrodynamics in a two-dimensional slab of finite width $L$ containing a homogeneous and isotropic dielectric medium with constant permittivity and permeability. We start from the known decomposition of modes in the nonaxion case and then solve perturbatively the governing equations for the electromagnetic fields to which the axions are also coupled. This is a natural approach, since the finiteness of $L$ destroys the spatial invariance of the theory in the $z$ direction normal to the plates. In this way we derive the value of the axion-generated rotation angle of the electric and magnetic fields after their passage through the slab, and use the obtained results to calculate the Casimir force between the two conducting plates. Our calculations make use of the same method as previously outlined in \cite{hoye20} for the case of Casimir calculations in chiral media and extend former results on the Casimir force in the Axion Electrodynamics.