Magneto-Plasmonics and Optical Sensing

Magneto-plasmonics explores the coupling between free-electron oscillations in metallic nanostructures and magnetic phenomena within adjacent or integrated magnetic materials. By combining plasmonic resonance with magneto-optical activity, this field seeks to amplify typically weak magnetic effects on light—such as Faraday rotation or the magneto-optical Kerr effect—at subwavelength scales. Enhanced interaction arises from confined electromagnetic fields at metal-dielectric interfaces, enabling sharper resonance features and increased modulation depths. These properties underpin novel optical sensors capable of detecting minute changes in refractive index, magnetic field strength or chemical binding events with high sensitivity and spatial resolution. Recent progress has seen the introduction of all-dielectric magnetic metasurfaces offering low-loss, high-quality-factor resonances, as well as hybrid magneto-plasmonic crystals designed for narrowband magnetic field detection. Together, these developments point to a new generation of compact, tunable photonic devices for biosensing, environmental monitoring and non-reciprocal optical components.

Research from Nature Portfolio

One study introduced an all-dielectric magnetic metasurface comprising bismuth-substituted iron-garnet nanopillars on an ultrathin film. The structure supports multiple quasi-waveguide and Mie-type resonances for both p- and s-polarised light, achieving quality factors exceeding those of plasmonic counterparts and enabling dual-polarisation magneto-optical modulation. A second work reported a one-dimensional magneto-plasmonic crystal formed by noble/ferromagnetic multilayers on a subwavelength grating. This design yields a narrow transverse magneto-optical Kerr effect band (≈50 nm) with a modulation depth above 4 % under modest magnetic fields, demonstrating magnetic field sensitivity down to 10^–6 Oe over millimetre-scale areas.

Magneto-Plasmonics and Optical Sensing publication trend

The graph below shows the total number of articles in magneto-plasmonics and optical sensing across all publications each year (not limited to Nature Index journals).

Technical terms

Plasmon: Collective oscillation of free electrons at a metal–dielectric interface driven by incident light.

Localized Surface Plasmon Resonance (LSPR): Strongly confined plasmonic oscillation in metallic nanoparticles or nanostructures that enhances local electromagnetic fields.

Faraday Rotation: Rotation of the polarisation plane of light as it propagates through a magnetised medium.

Magneto-Optical Kerr Effect (MOKE): Change in reflected light intensity or polarisation from a magnetised surface, often used for sensing.

Metasurface: Two-dimensional arrangement of subwavelength resonators engineered to control amplitude, phase or polarisation of light.

Bound States in the Continuum (BICs): Non-radiating resonant modes embedded within a continuum of radiation states, supporting high-quality factors.

References

1. All-dielectric magnetic metasurface for advanced light control in dual polarizations combined with high-Q resonances. Nature Communications (2020).
2. Magnetic field sensor based on magnetoplasmonic crystal. Scientific Reports (2020).
3. Extreme Nonreciprocity in Metasurfaces Based on Bound States in the Continuum. Advanced Optical Materials (2023).
4. Nanophotonic devices based on magneto-optical materials: recent developments and applications. Nanophotonics (2022).