Enhancement of the magneto-optical activity via surface plasmon resonance on Au-Co nanocomposite thin films

Appropriately designed metallic nanoparticle arrays and thin films are suitable platforms for sensing applications based on their optical, magneto-optical (MO) and magneto transport properties. For example most current biosensing schemes based on optical excitation of surface plasmon resonance (SPR) are "passive", i.e., they are based on changes in the optical properties at the sensor surface typically gold- when a biological specimen to be detected is bound to it and SPR is excited. We have shown that it is possible to enhance the sensitivity of these thin films by combining Au with other materials that exhibit changes under suitable external modulation hence developing "active" plasmonic surfaces. In such scenario, optimal combination of materials can exhibit enhanced optical as well as electrical transport properties. Here, such physical properties, i.e. optical and electric transport, have been investigated. in Au-Co nanocomposite thin films after modifying growth parameters such as growth temperature and relative Au:Co concentration. We found that suitable combinations of these two materials can exhibit enhanced MO effects and in some cases also substantial magneto resistance, the latter of interest for sensing magnetic media. Thus, here we have applied theoretical models to simulate the optical properties in the nanocluster-matrix aggregation and compared with the experimental optical data. Correlation between the nanocomposite films' microstructure, morphology, optical, MO enhancement and magneto-transport is discussed.