MAGNETIC-ORDERING IN MULTILAYER MONOATOMIC CO/CU FILMS

The magnetic properties of monoatomic (approximately 0.3 nm) cobalt layers were studied in multilayer Co/Cu and Co/SiO2 systems and in a three-layer Cu/Co/Cu film structure. The saturation magnetization M and nuclear spin-spin relaxation times T2 were measured as functions of the copper layer thickness d(Cu). Also the frequency spectra of spin-echo signals from Co-59 nuclei were measured. The main result obtained was experimental evidence for the effect of copper conduction electrons on magnetic ordering in cobalt, which is strongly dependent on d(Cu). For d(Cu) = 0.2-0.3 nm, multilayer structures with monoatomic Co layers exhibit three-dimensional (spatial) properties. As d grows, their properties transform first into quasi-two-dimensional ones, and further into such states when they are probably determined by the quantum size effect for each individual Co layer.