Magneto-optical effects in second harmonic generation from W/Co/Pt nanofilms

Interfaces between ferromagnetic metals and nonmagnetic specimen attract much attention as they are very important for the formation of magnetic properties of nanostructures. Vice versa, specific magnetic ordering at such interfaces may provide new effects in their optical and nonlinear optical response. In this work we study the magnetization-induced effects in optical second harmonic generation (SHG) in W/Co/Pt-based thin films with the thicknesses of the Co layer of 2 – 10 nm. Besides common odd in magnetization effects in the SHG intensity, we observe additional one that is not expected for homogeneously magnetized ferromagnetic films, which consists in modulation of p-polarized SHG intensity under longitudinal magnetic field application. The phenomenological description of the observed effect is performed in terms of gradient and second-order in magnetization contributions to the SHG polarization, where gradient of magnetization along the normal to the structure plays the key role.

Magnetic Field Application to Increase Yield of Microalgal Biomass in Biofuel Production

Use of fuels from non-renewable sources has currently been considered unsustainable due to the exhaustion of supplies and environmental impacts caused by them. Climate change has concerned and triggered environmental policies that favor research on clean and renewable energy sources. Thus, production of third generation biofuels is a promising path in the biofuel industry. To yield this type of biofuels, microalgae should be highlighted because this raw material contains important biomolecules, such as carbohydrates and lipids. Technological approaches have been developed to improve microalgal cultivation under ecological conditions, such as light intensity, temperature, pH and concentrations of micro and macronutrients. Thus, magnetic field application to microalgal cultivation has become a viable alternative to obtain high yields of biomass concentration and accumulation of carbohydrates and lipids.