  Two-dimensional double nanoparticles (DNPs) arrays are demonstrated
theoretically supporting the interaction of out-of-plane magnetic plasmons and
in-plane lattice resonances, which can be achieved by tuning the nanoparticle
height or the array period due to the height-dependent magnetic resonance and
the periodicity-dependent lattice resonance. The interplay of the two plasmon
modes can lead to a remarkable change in resonance lineshape and an improvement
of magnetic field enhancement. Simultaneous electric field and magnetic field
enhancements can be obtained in the gap regions between neighboring particles
at two resonance frequencies as the interplay occurs, which present open
cavities as electromagnetic field hot spots for potential applications on
detection and sensing. The results not only offer an attractive way to tune the
optical responses of plasmonic nanostructure, but also provide further insight
into the plasmons interactions in periodic nanostructure or metamaterials
comprising multiple elements.
