Evolution of magnetic and structural properties from Ag nanolayers to several microns Co–Ag deposits prepared by electrodeposition

The evolution of composition, morphology, magnetic properties and crystalline structure of Co–Ag electrodeposits from nanometric to micrometric thicknesses has been analyzed. Different substrates (Si/Ti/Ni, Si/Cr/Cu and glass/ITO) have been used to electrodeposit the Co–Ag system. The same trend was observed in all cases: after a first nanometric silver layer, cobalt was gradually incorporated till constant composition was attained. Moreover, a gradual variation of the magnetic response of the films from diamagnetism to superparamagnetism and then ferromagnetism was detected by increasing the deposition charge. fcc-Ag, hcp-Co and a metastable phase hcp-CoAg3 were present in Co–Ag micrometric deposits grown over Si/Ti/Ni from the very early deposition stages, these deposits showing coercivity values around 115 Oe. However, deposits of lower coercivities (around 50 Oe) were obtained over glass/ITO and Si/Cr/Cu substrates, these deposits being constituted by fcc-Ag and hcp-Co.