Giant Kerr Rotation Enhancement in Magneto-plasmonic Metamaterials

Abstract

Abstract:We report for the first time an order of magnitude enhancement of Kerr rotation in hybrid plasmonic/ferromagnetic metamaterial resonators. Our results pave the way towards magnetically controlled metamaterials and integrated magneto-plasmonics. Interfacing plasmonic and magneto-optical materials has recently emerged as a promising approach towards active nanoscale optical elements with significant technological implications: optical isolators, modulators, data storage, sensing, imaging, therapy. Such hybrid systems combine the strong local fields at the plasmonic resonance with the magneto-optical response of ferromagnetic layers leading to magnetic control of the plasmonic response or vice-versa [1,2]. Here we demonstrate direct integration of magneto-optical materials in metamaterial resonators leading to an order of magnitude enhancement of the polar magneto-optical Kerr effect (MOKE).The system under study is a periodic array of bi-metallic Au/Ni plasmonic ring resonators, where the gold part provides a strong plasmonic response, while the nickel section is responsible for the magneto-optical effects. Taking into account the high losses of Ni which damp the plasmonic response of the resonators, as well as current manufacturing and measuring limitations, we fix the composition of the rings to ¾ Au and ¼ Ni (see Fig. 1a). The sample was fabricated by a multi-step procedure comprising e-beam lithography, film evaporation, and lift-off processes. The manufactured sample consists of bi-metallic rings with a mean diameter of 200 nm and a cross-section of 50x50 nm 2 . The unit cell is 400x400 nm 2 , while the overall size of the array is 100x100 µm 2 . Polarization azimuth rotation spectra due to the polar magneto-optical Kerr effect in the presence of a BDC=200 mT external magnetic field. Blue points correspond to a 50 nm thick Ni film and red to the bimetallic metamaterial array. Lines serve as guides for the eye. Inset: Numerically simulated electric field map of the metamaterial unit cell at resonance.

Novel layout of a bi-metallic nanoring for magnetic field pulse generation from light

“…The configuration studied here is a bi-metallic nanoring sitting on a silica substrate (see figure 1). This corresponds to a fabricated structure recently reported [15]. We investigate both the 2-sectors and 4-sectors nanorings and the nickel sector angular extent θ is varied (in the 2-sectors design the gold sector extends over 2π-θ while in the 4-sectors design the two gold sectors extend each over π-θ).…”

Terahertz magneto-optical response in ferromagnetic Fe–Co–Al alloys

“…Therefore, one can use the direction of magnetization to control the way in which light reflects from a surface of a magnet. This effect has been used in memory storage devices [3,4] and in the creation of tunable photonic materials [5,6].…”

Au-Encapsulated Fe Nanorods in Oxide Matrix with Tunable Magneto-Optic Coupling Properties

“…To this end, various magneto-optic coupling materials have been fabricated, such as single-phased thin films (e.g., Fe and Ni), − multilayer films (e.g., Fe/Cr/Fe and Au/Co/Au), , and nanostructured films (e.g., split-ring nanoantennas). , Among these candidates, nanostructures with magneto-optic coupling have received considerable interest due to their unique geometry that are used in applications such as label-free detection in biosensors , and high-speed applications in communication devices. , These nanostructures typically consist of either one or multiple metals fabricated into different arrays consisting of nanodisks, − nanoparticles, , or nanorods. , By fabricating these metals into different nanostructures, their plasmon response is enhanced and new functionality emerges . Typically, lithography and multistep growth are used to fabricate these different structural arrays. − …”