STRUCTURAL-PROPERTIES OF MOLECULAR-BEAM EPITAXY-GROWN NI PT SUPERLATTICES/

We find that the [Ni3.2nmPt1.6nm] X 15 and [Ni3.2nmPt0.8nm] X 15 multi layers are semicoherent and display a columnar morphology. From both t he period of the moire fringes and the positions of the diffraction pe aks in electronic (plan-view and cross-section geometries) and x-ray d iffraction patterns, one deduces that the nickel is relaxed (at least in the error bars of all our measurements), whereas the platinum remai ns slightly strained (approximate to-1%). The interfaces are sharp; no intermixing takes place giving rise to neat contrasts in transmission electron microscopy (TEM) and to high intensities of the superlattice peaks in the growth direction in both diffraction techniques. The rel axation of the interfacial misfit occurs partially through misfit disl ocations, partially through the strain of platinum. A quasiperiodic tw inning occurs at the interfaces, the stacking fault which forms the tw in being the most often located at the interface Pt/Ni, i.e., when a P t layer begins to grow on the Ni layer. The simulation of the theta/2 theta superlattice peak intensities takes into account the columnar mi crostructure. It shows that the roughness is predominantly at medium s cale with a fluctuation of about 12.5% for Ni layers and negligible fo r Pt layers.