Surface plasmons and magneto-optic activity in hexagonal Ni anti-dot arrays

TL;DR

This study demonstrates that surface plasmons in hexagonal Ni anti-dot arrays significantly enhance magneto-optic Kerr rotation, with the pattern's symmetry influencing plasmonic coupling, supported by experiments and theoretical analysis.

Contribution

It provides new insights into how surface plasmons in patterned ferromagnetic films enhance magneto-optic effects, highlighting the role of hexagonal symmetry in plasmonic coupling.

Findings

Surface plasmons cause pronounced reflectivity troughs.

Plasmonic excitations strongly enhance Kerr rotation.

Hexagonal symmetry affects plasmonic coupling and optical activity.

Abstract

The influence of surface plasmons on the magneto-optic activity in a two-dimensional hexagonal array is addressed. The experiments were performed using hexagonal array of circular holes in a ferromagnetic Ni film. Well pronounced troughs are observed in the optical reflectivity, resulting from the presence of surface plasmons. The surface plasmons are found to strongly enhance the magneto-optic response (Kerr rotation), as compared to a continuous film of the same composition. The influence of the hexagonal symmetry of the pattern on the coupling between the plasmonic excitations is demonstrated, using optical diffraction measurements and theoretical calculations of the magneto-optic and of the angular dependence of the optical activity.