Optical and magneto-optical properties of Fe nanoparticles

Abstract

The optical and magneto-optical properties of Fe nanoparticles with sizes ranging from 2 to 8 nm, embedded in amorphous Al 2 O 3 , are studied as a function of their size and shape. The optical properties were measured using spectroscopic ellipsometry, whereas the magneto-optical properties were determined in two different Kerr configurations: polar and transverse. A generalization of different effective medium approximations is used to describe and analyze experimental data in nanocomposite media. In this generalization, the shapes of the nanoparticles are considered as an input parameter. The optical and magneto-optical parameters show clearly different values as a function of the nanoparticle size. A reasonable agreement between the theoretical calculations and experimental data is found when the average size of the nanoparticles is larger than 4 nm. On the other hand, the experimental and theoretical curves differ for smaller sizes, implying that below 4 nm the optical and magneto-optical constants of the particles deviate from the bulk behavior.

Magnetic properties of cobalt and cobalt–platinum nanocrystals investigated by magneto-optical Kerr effect

“…Despite their interest, studies of the optical and magneto-optical properties of ferromagnetic nanoparticles are scarce. [13][14][15][16] Only recently Kalska et al 17 reported magneto-optics at room temperature of self-organized cobalt nanocrystals deposited on silica. However, to date none of these organizations of ferromagnetic nanocrystals can be used at room temperature.…”

Size mediated control of the optical and magneto-optical properties of Co nanoparticles in ZrO2

“…22 Note that the concentration of nanoparticles must be lower than 50%; if it is higher it must be considered as the matrix element. Therefore, from the measured optical and MO constant of the layers ͑Figs.…”

“…Since the sizes of the Co nanoparticles inside the layers are much smaller than the wavelength of the incident light we can use an effective medium approximation 21 that takes into account the Co concentration dependence to obtain the optical and MO properties of the Co located inside the layers. In the Maxwell-Garnet approximation the effective dielectric tensor e of a composite material consisting of particles randomly distributed in a matrix depends on the dielectric tensors of the particles and matrix, and concentration and shape of the particles [21][22][23] as follows:…”

Synthesis of tunable plasmonic metal-ceramic nanocomposite thin films by temporally modulated sputtered fluxes

“…The LSPR gives rise to a strong absorption around the resonance energy 1 and can lead to an intense coloration of the material 2 . It also results in a strong localized enhancement of the electric field around the nanoparticles making these materials interesting for a number of applications, such as sensors 3 , absorbers [4][5][6] , substrates for surface enhanced Raman scattering 7 , optically active materials 8,9 and materials exhibiting an enhanced magnetooptical coupling 10 . The energy position and width of the absorption, as well as the plasmonic properties in such a nanocomposite, depend on the dispersion of the electromagnetic radiation in the dielectric matrix in combination with the bulk optical properties of the metal nanoparticle, the nanoparticle size and shape, and the inter-particle separation 11,12 .…”