This book presents the theory, design, fabrication, measurement, and characterization of ferromagnetic hybrid multilayers and granular alloys consisting of magnetic, non-magnetic, and dielectric material that are significant in the development of next generation state-of-the-art magnetic sensors. Topics on artificial generation of magnetic anisotropy through oblique angle deposition and induced strain are also covered. It also covers topics on nanocomposite material and high-magnetic-moment biocompatible alloys, artificially produced on polyimide, and considered useful for potential clinical applications. The future of magneto-optic based ferromagnetic nanostructures is extremely bright. The exceptional properties displayed by magneto-optic (MO) nanostructures, such as strong enhancement of electromagnetic fields, high sensitivity, and large signal-to-noise-ratio, make them unique, outstanding, and sought for material for biosensing, imaging and many other applications. New chapters are added on surface plasmon resonance (SPR) and MO-SPR configurations and bio-sensing.