Coordinated RHEED, XRD, and FMR investigations of MBE grown Co–Cu (100) superlattices

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Abstract
A sequence of fcc, 〈100〉 oriented, [Co (50 Å)–Cu (X)] superlattices with X=25–200 Å, was grown by molecular beam epitaxy on Cu(100)/Si(100) substrates. In‐plane 33.4 GHz ferromagnetic resonance (FMR) data were analyzed to determine the perpendicular uniaxial magnetic anisotropy field (Hu) and cubic anisotropy field contributions. The Hu values were found to be negative, indicating that the film normal is a magnetic hard axis. The magnitude of Hu depended on the Cu layer thickness. Superlattice x‐ray‐diffraction and reflection high‐energy electron‐diffraction patterns were analyzed. The measured strain data for Co superlattice layers, in combination with known elastic and magnetostriction constants for bulk fcc Co, yield calculated strain‐induced Hu values which agree well with those obtained from the FMR. The observed Hu values, which are affected by the Cu layer thickness, approach a constant for Cu thickness ≥100 Å.