Theory of Spoof Magnetic Localized Surface Plasmons Beyond Effective Medium Approximations

TL;DR

This paper introduces a theoretical approach to replicate magnetic localized surface plasmons using high-index dielectrics instead of negative permeability metamaterials, enabling practical subwavelength magnetic devices at microwave frequencies.

Contribution

It demonstrates analytically that MLSP resonances can be mimicked by homogeneous high-index dielectrics, bypassing limitations of negative permeability metamaterials.

Findings

Homogeneous high-index dielectric spheres can reproduce MLSP electromagnetic distributions.

The approach enables practical subwavelength magnetic photonic devices.

Potential applications in radiofrequency and microwave regions.

Abstract

A homogeneous negative permeability sphere can support magnetic localized surface plasmons (MLSPs). Generally, negative permeability materials are metamaterial (MM) structures exhibiting very deep subwavelength spatial scales, whose effects may be detrimental in the near-field for those applications based on effective medium approximations. We suggest to overcome this fundamental limitation by demonstrating analytically that the electromagnetic spatial distribution, associated to a MLSP resonance and excited by a near-field source, can be accurately reproduced outside the sphere by substituting the negative permeability sphere with a homogeneous high-index dielectric one with the same radius. Considering that a large class of ferroelectric materials shows ultra-high dielectric constant and low-losses at low frequency (up to GHz), our spoof MLSPs theory could be a key tool for realizing high performance subwavelength magnetic photonic devices in the radiofrequency and microwave regions.