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We have investigated the magnetic anisotropy and interlayer coupling in trilayer films of permendur(100Å )/Ru/permalloy(100Å ), with the thickness of the Ru spacer varying from 0 to 200Å . While the permendur/permalloy sample exhibits a small in-plane uniaxial magnetic anisotropy with Hu=27 Oe, all trilayers are magnetically isotropic in-plane. Results from hysteresis loop and ferromagnetic resonance measurements were fitted to a micromagnetic model, with the results indicating that all the films are ferromagnetically coupled except the one with 10Å Ru spacer, which shows antiferromagnetic coupling. The trilayers with Ru spacer layer thickness larger than 20Å exhibit only very weak ferromagnetic coupling. [ABSTRACT FROM AUTHOR]

Magnetic coupling in trilayer films of FeNi/Cu/FeCo deposited on Si/SiO2 substrates have been studied. While the thicknesses of the FeNi and FeCo layers were kept constant at 100Å, the thickness of the Cu spacer was varied from 5 to 50Å. Both hysteresis loop and ferromagnetic resonance results indicate that all films are ferromagnetically coupled. Micromagnetic simulations well reproduce the ferromagnetic resonance mode positions measured by experiments, enabling the extraction of the coupling constants. Films with a thin Cu spacer are found to be strongly coupled, with an effective coupling constant of 3erg/cm² for the sample with a 5Å Cu spacer. The strong coupling strength is qualitatively understood within the framework of a combined effect of Ruderman-Kittel-Kasuya-Yosida and pinhole coupling, which is evidenced by transmission electron microscopy analysis. The magnetic coupling constant surprisingly decreases exponentially with increasing Cu spacer thickness, without showing an oscillatory thickness dependence. This is partially connected to the substantial interfacial roughness that washes away the oscillation. The results have implications on the design of multilayers for spintronic applications. [ABSTRACT FROM AUTHOR]