  A broken symmetry is generally believed to be a prerequisite of plasmonic
electromagnetically-induced transparency (EIT), since the asymmetry renders the
excitation of the otherwise forbidden dark mode possible. Nevertheless,
according to the picture of magnetic-plasmon resonance (MPR) mediated plasmonic
EIT, we show that the plasmonic EIT can be achieved even in the symmetric
structures based on the second-order MPR. This sharpens our understanding of
the existing concept, but also a profound insight into the plasmonic coherent
interference in the near-field zone.
