Twin formation in Ag seeded Co/Pt multilayers grown on GaAs by molecular beam epitaxy

Molecular beam epitaxy was used to grow ultrathin Co-Pt multilayers on GaAs (111) substrates with 200 Å thick Ag layer as a buffer. Magnetic properties (B-H loop) of the multilayers, measured by a vibrating sample magnetometer, confirmed that these samples exhibit strong anisotropy perpendicular to the film surface. Reflection high energy electron diffraction and low-energy electron diffraction showed that twin-related Ag grains nucleated on the substrates. The epitaxial relationship of the multilayers with respect to the substrate was investigated by high-resolution transmission electron microscopy. Twin-related grains, 30-40 nm in diameter, are present in the multilayers. These twins are generated either by propagation of existing twin boundaries in the Ag layer into the multilayers or by nucleation of twin-related Pt grains on the Ag buffer surface.