OSCILLATORY FERROMAGNETIC INTERLAYER COUPLING OF FE(110) THIN-FILMS THROUGH (111) ORIENTED AG AND CU SPACERS

The magnetic coupling of Fe(110) thin films through epitaxial (111) or iented noble-metal spacers has been investigated using a site-specific Mossbauer spectroscopy technique that is sensitive to changes in the interfacial Fe spin-wave spectrum. As the interlayer exchange oscillat es, the interfacial spin-wave modes are alternately softened and stiff ened. To qualitatively connect the observed spin-wave behavior to the effective exchange al the Fe/noble-metal interface, the system is mode led using two semi-infinite simple cubic ferromagnets which may intera ct either ferromagnetically or antiferromagnetically. Vibrating-sample magnetometry and superconducting quantum interference device magnetom etry measurements determined that the interlayer coupling is always fe rromagnetic. As the interlayer thickness is increased, the spin-wave b ehavior indicates an oscillatory component superimposed on a monotonic decrease in the ferromagnetic exchange coupling. The periodicities of the oscillatory component are 6 monolayers (ML)) for Ag(111) and 4.5 ML for Cu(111), in close agreement with the expected periodicities fro m the bulk Fermi-surface spanning vectors.