Tunable multiple Fano resonances in magnetic single-layered core-shell particles

TL;DR

This paper analyzes how magnetic core-shell nanoparticles can exhibit tunable multiple Fano resonances, with potential for external control via magnetic material properties, expanding understanding of scattering phenomena in nanostructures.

Contribution

It provides an analytical condition for comblike resonances in magnetic coated spheres and demonstrates their tunability and robustness beyond the long-wavelength limit.

Findings

Comblike scattering resonances depend on magnetic permeability and shell thickness.

Resonances are robust against absorption effects.

External tuning of resonances is possible through magnetic material properties.

Abstract

We investigate multiple Fano, comblike scattering resonances in single-layered, concentric core-shell nanoparticles composed of magnetic materials. Using the Lorenz-Mie theory, we derive, in the long-wavelength limit, an analytical condition for the occurrence of comblike resonances in the single scattering by coated spheres. This condition establishes that comblike scattering response uniquely depends on material parameters and thickness of the shell, provided that it is magnetic and thin compared to the scatterer radius. We also demonstrate that comblike scattering response shows up beyond the long-wavelength limit and it is robust against absorption. Since multiple Fano resonances are shown to depend explicitly on the magnetic permeability of the shell, we argue that both the position and profile of the comblike, morphology-dependent resonances could be externally tuned by exploiting the properties of engineered magnetic materials.