MAGNETIC DECOUPLING IN SPUTTERED FE/SI SUPERLATTICES AND MULTILAYERS

Sputtered Fe/Si superlattices were grown to study the magnetic coupling between ferromagnetic Fe layers (30 angstrom thick) for Si spacer-layer thicknesses (t(Si)) between 10 and 40 angstrom. The material is ferromagnetical for t(Si) < 13 angstrom and antiferromagnetically coupled for 13 angstrom < t(Si) < 17 angstrom. For t(Si) > 17 angstrom the Fe layers are uncoupled. X-ray analysis indicates that the system is well layered, but that the crystal structure remains coherent only for t(Si) < 17 angstrom. These results, along with our Mossbauer investigation, strongly suggest that the Si layer is crystalline for t(Si) < 17 angstrom, and is silicide in nature. For thicker spacers, Si becomes amorphous. We propose a model of the layering that is consistent with the known properties of Fe silicide.