Magnetic susceptibility of fe/cu multilayers : ferromagnetic, antiferromagnetic, and spin-glass phases

Abstract

In this work we present low-field magnetic measurements on multilayers of Fe 1.5 nm and Cu 1.5 nm layers, repeated 10 times, grown on Si~111! and Fe 5 nm/CaF2 40 nm/Si(111), substrates. Magnetic characteristics of a spin-glass phase are exhibited by samples directly grown on Si (111), for which the glass temperatures (TG) depend strongly on the magnetic field. Above TG those samples exhibit a ferromagnetic behavior. In contrast, samples grown on Fe/CaF2 buffer structure also show the spin-glass characteristics, but are antiferromagnetic above TG . This work deals with the fundamental role played by the interface between Fe and Cu for these effects, which is clearly emphasized by the experimental results.