Light localisation and magneto-optic enhancement in Ni anti-dot arrays

TL;DR

This study demonstrates how nano-patterned Ni surfaces can localize light and enhance magneto-optical effects through surface plasmon polaritons, with spatial mapping revealing polarization-dependent near-field distributions.

Contribution

It provides direct spatial mapping of electric near-fields on Ni nano-patterns and links plasmon excitation to magneto-optical enhancement, revealing polarization-dependent effects.

Findings

Near-field concentrates in hexagonal lattice spots or stripes.

Surface plasmon polaritons enhance Kerr effect.

Polarization controls near-field distribution.

Abstract

The excitation of surface plasmons in magnetic nano-structures can strongly influence their magneto-optical properties. Here, we use photoemission electron microscopy to map the spatial distribution of the electric near-field on a nano-patterned magnetic surface that supports plasmon polaritons. By using different photon energies and polarization states of the incident light we reveal that the electric near-field is either concentrated in spots forming a hexagonal lattice with the same symmetry as the Ni nano-pattern or in stripes oriented along the $\Gamma$-K direction of the lattice and perpendicular to the polarization direction. We show that the polarization-dependent near-field enhancement on the patterned surface is directly correlated to both the excitation of surface plasmon polaritons on the patterned surface as well as the enhancement of the polar magneto-optical Kerr effect.