Thickness-Dependent Structural and Magnetic Study of Co/Si/Co Trilayers Grown by Ion Beam Sputtering

The magnetic properties of the metal/semiconductor structure can be modulated by the semiconductor layer thickness and therefore in the present paper, a series of trilayers of ion beam sputtered Cobalt-Silicon-Cobalt (Co/Si/Co) were grown to study the interface characteristics and their connections with magnetic properties. The thickness of Co layer, t(Co), is fixed to 3 nm, while varying the thickness of Si sandwich layer, t(Si), from 1.5 nm to 4 nm, reflectively. Grazing incidence X-ray diffraction (GIXRD), grazing incidence X-ray reflectivity (GIXRR), Atomic Force Microscopy (AFM) and Magneto-Optic Kerr Effect (MOKE) techniques were employed to study the crystal structure, surface and interface structure, morphology and magnetic characteristics of thin films. X-ray reectivity measurements show substantial intermixing between the layers leading to trilayers of complicated structure at the interface during deposition. At t(Si) = 1: 5 nm, whole Si layer is converted into silicide, whereas at higher spacer layer thickness (t(Si)), in addition to silicide layer, an unreacted elemental layer of Si also remains in the spacer. A magneto-optical measurement reveals the presence of anti-ferromagnetic coupling in these samples and the strength of coupling between Co layers is found to be depended on t(Si).