F. J. Lamelas

Interface anisotropy in cobalt‐based epitaxial superlattices

We have measured the magnetic anisotropy in a series of Co‐Au and Co‐Cu superlattices prepared by molecular‐beam epitaxy. Significant epitaxial strains give rise to a magnetoelastic contribution and a large crossover thickness (∼19 A) for perpendicular easy magnetization. The results are discussed in the context of a careful analysis of the interfacial strains and coherence determined by in situ. time‐resolved reflection high‐energy electron diffraction techniques and x‐ray scattering.

X-ray scattering and absorption studies of epitaxial strains in Co-Au superlattices

Abstract X-ray scattering and EXAFS are used to probe epitaxial strain in Co-Au superlattices grown by molecular beam epitaxy. We observe a thickness-dependent strain in ultrathin cobalt layers and find that tensile strains near misfit dislocations may be larger than in the more coherent interior of the Co layers. A strong enhancement of the magnetic absorption spectrum is observed in the superlattice samples.

Epitaxy of Co-Metal Superilattices

Magnetic superlattices are of great current interest due to the improvement of crystal growth techniques for their preparation and their potential for practical applications in high density magnetic recording. It is apparent that a strong correlation exists between structural and magnetic properties of these supcrlattices. Careful sample preparation and structural characterization arc necessary in order to tailor their magnetic properties. Molecular Beam Epitaxy (MBE) provides the capability for controlled crystal growth and in-situ strtuctoral, chemical and physical characterization. Ex-situ techniques such as X-ray diffraction and high-resolution TEM, also provide insight into interfaces in these structures. Co layers sandwiched with Au, Cu and Pt layers of various thickness are discussed in this paper.

Structural and Magnetic Properties of Epitaxial Co-Au Superlattices

We describe measurements on the structural and magnetic properties of Co–Au superlattices grown on Ge–buffered (110) GaAs by molecular beam epitaxy. Samples have been prepared with Co layer thicknesses ranging from 5–40A and Au spacer layers of constant thickness, ∼ 16A. X–ray scattering and high-resolution transmission electron microscopy show that the hcp Co layers grow epitaxially with the (0001) axis parallel to (111)Au and with the in–plane Co[11 2 0] axis parallel to GaAs[001]. SQUID magnetometer measurements reveal a crossover in the magnetic anisotropy of the as–grown samples such that the easy axis is perpendicular to the substrate plane when the Co layer thickness is less than ∼19A.