An investigation of magneto-optical Kerr effect signal by optical cavity in [Glass/Co/ZnS] structure

Highlights: • Samples were simulated based on TMM, to obtain the optimal thicknesses for each layer. • The hysteresis loops of samples have been measured, confirming the simulation results. • Amplifying the MOKE using the non-magnetic layer is provided by formation of an optical cavity. • The Glass/Co/ZnS multilayers can act as a highly accurate magneto-optical sensor. In this paper, using the magneto optical Kerr effect, the magnetic properties of [Glass/Co/ZnS] structure has been investigated. Initially, by co-precipitation method, zinc sulfide was prepared and then by X-ray diffraction pattern, its structure was confirmed. In the structure of [Glass/Co/ZnS], cobalt was used as a magnetic material and zinc sulfide acts as a capping layer. Before fabrication process, the optimums cobalt and zinc sulfide thicknesses were calculated using the MATLAB simulation software and the desired thicknesses were selected. To obtain layers with variable thicknesses, the oblique thermal evaporation technique was used and different thicknesses of about 5–90 nm for cobalt and 45 nm for zinc sulfide on the glass substrate were coated. The longitudinal Kerr signal (LKS) of the [Glass/Co/ZnS] samples were measured in different cobalt thicknesses. By using the magneto-optical Kerr effect (MOKE), the hysteresis loop of samples in the longitudinal geometry have been measured samples and it was observed that the sample has an easy axis in the plane of the film and in the direction of its large diameter. The results have shown that the capping layer with suitable thickness, by creation of an optical cavity, has been able to amplify the Kerr signal by more than 1.5 times, which is noticeable by considering the simplicity of the technique. This structure can be applied as a highly accurate magneto-optical sensor.