Mimicking localized surface plasmons via mie resonances to enhance magnetic-resonance-imaging applications

Metaphotonics, combining metamaterial (MM) and nanophotonic concepts, offers a unique platform for obtaining an unusual and/or advantageous electromagnetic response on a scale much less than the wavelength, although several practical applications are strongly hampered by the complexity of fabrication of MM devices and the intrinsic subwavelength inhomogeneous response of the MM composite. Recently, much research effort has been focused on the study of photonic devices for magnetic resonance imaging (MRI), one of the cornerstone diagnostics techniques in life science. In the MRI context, we introduce the use of magnetic surface excitations (magnetic localized surface plasmons) supported by a negative-magnetic-permeability MM sphere that results in a significant local enhancement of the MRI signal-to-noise ratio. Using the Mie resonance theory, we show that an increase in the signal-to-noise ratio boost can be obtained by replacing the MM sphere with a homogeneous high-permittivity one of the same radius. Overcoming some of the main MM limiting factors, our results suggest a simple approach for the realization of radio-frequency magnetic metadevices.