  Axionic electrodynamics predicts many peculiar magnetoelectric-based
properties. Hitherto, simple structures such as one-dimensional multilayers
were employed to explore these axionic magnetoelectric responses, and
Fabry-P\'{e}rot interference mechanism was frequently applied to augment these
effects. In this Letter, we propose a new mechanism, metamaterial-enhanced
axionic magnetoelectric response, by taking advantage of intense enhancement of
localized electromagnetic fields associated with plasmonic resonances. Through
numerical simulations, we show that plasmonic metamaterial can enhance axionic
magnetoelectric effect by two orders of magnitude.
