Magnetic plasmons in a simple metallic nanogroove array for refractive index sensing

Magnetic plasmons (MPs) refer to the coupling of external electromagnetic waves with a strong magnetic response induced inside the nanostructures. MPs have been widely employed as artificial magnetic atoms to fabricate negative-permeability or negative-refractive-index metamaterials with peculiar electromagnetic properties. Here, we propose a refractive index sensing by utilizing the MP resonances excited in a simple one-dimensional (1D) metallic nanogroove array. We demonstrate a sensitivity up to 1200 nm/RIU with a figure of merit (FOM*) of 15 thanks to the MP resonances that are extremely sensitive to the surrounding media. Importantly, the influence of the local environment effects on the sensing ability is studied. An equivalent inductor-capacitor (LC) model is used to give a precise quantitative description of the sensing performance and reveal the underlying mechanism. Such a MP-based sensor with the ease of fabrication may provide great potentials in designing broadband sensing devices with high performance and compactness.