Crystallography of Co/Pt Multilayers and Nanostructures

Atomically engineered nanostructures and multilayers of Co/Pt exhibit strong perpendicular anisotropy. This unique property, that determines their potential as a magneto-optic recording medium, is dependent on a variety of microstructural parameters that include the overall crystallography, thickness of the layers, orientation, defect formation, interface reactions, etc. A series of Co/Pt multilayer samples with different thickness of the Co layer were studied by electron diffraction. It has been determined that the Co layers persist in the fcc structure up to 50 Å thickness. As the thickness is varied from 3 to 50 Å in the multilayers, the Co film gradually relaxes to its bulk lattice parameter. (Ill) twinning and lattice strain at the interfaces between Pt and Co layers are also observed. The symmetry-forbidden reflections observed at https://www.w3.org/1998/Math/MathML" display="inline"> 1 3 {224} positions in [111] zone diffraction patterns of the multilayer are due to (111) twinning and compositional modulations along the multilayer growth direction.