Enhanced magneto-optical properties of Fe3O4@Au nanoparticles and its reverse core-shell nanostructure embedded in host matrix SiO2

Abstract

We studied the effect of electric and magnetic polarizability of Fe3O4@Au and the reverse structure Au@Fe3O4 core-shell spherical nanostructures embedded in SiO2. Employing electrostatic approximation and Maxwell-Garnett effective medium theory, we evaluate the electric and magnetic polarizability, the refractive index and absorbance as a function of radiation energy. The modified Drude-Lorentz form and Lorentz model used to evaluate ϵ(ω) and μ(ω), respectively. For fixefd r2 = 30 nm, β = 0.875, εh = 3.9 and f = 0.001 maximum absorbance obtained at E = 2.742 eV for Au@Fe3O4 core-shell and at E = 2.937 eV for the reverse structure with β = 0.578. The ratio of the maximum absorbance peak of Au@Fe3O4 core-shell to Fe3O4@Au core-shell gives 3.5. Both graphs of n2 and absorbance possess three sets of peaks. All sets of resonance peaks of Fe3O4@Au found in the visible region. For the revers structure the first two sets of resonance peaks found in the visible region and the third set of resonance peaks in UV region. The peaks arise due to the coupling between the surface plasmon of the gold metal with Fe3O4∕SiO2 interfaces and the interaction of incident radiation with magnetic dipole moment of the magnetic semiconducting nanoparticles. The findings may be used in applications that require the combined plasmonic and magnetic effects such as drug delivery.