Interfacial interactions of FeCo/Pd and FeCo/Ru multilayers

The FeCo system of alloys is perched atop the Slater-Pauling curve. As a result of this and its relatively low cost and ease of deposition, it is heavily used within the magnetic recording industry. However, new technology requires an advance past this system with respect to high moment, high magnetization materials. One possible step is the enhancement of the FeCo system. One approach is the lamination of thin, nonmagnetic Pd spacer layers with FeCo. Prior published results have shown an increase in not only the moment, but also the magnetization of the samples. We have developed a FeCo/Pd superlattice samples to test this hypothesis. Our results, using a combination of conventional magnetometry, x-ray magnetic circular dichroism, and polarized neutron reflectivity, show a different result from prior reports. The magnetic dichroism experiments show a definite decrease in the magnetic moments of both the Fe and Co with the introduction of Pd. The preliminary analysis of the neutron reflectivity data shows no increase in the magnetic moment of the alloy, nor an induced moment in the Pd. For comparison with the FeCo/Pd superlattice, we studied an antiferromagnetically coupled FeCo/Ru superlattice.