Effect of in-plane magnetic anisotropy on crystal structure in cobalt thin films deposited on LiTaO₃ substrates

We investigate the relationship between the in-plane uniaxial magnetic anisotropy ( K u ) and the crystal structure of Co thin films with thicknesses ( t ) ranging from 5 to 21 nm deposited on LiTaO₃ (LTO) single-crystal substrates with different cut angles (42° and 36° Y-cut, and 112° X-cut) using RF magnetron sputtering. On the 42LTO/Co, the Co film ( t = 9.5 nm) exhibited a preferential orientation of fcc-Co (111), and the K u peaked at 2.45×10⁵ erg/cm³. With increasing thicknesses, the fcc-Co (111) grains grew more randomly with respect to the (011 ̅2) plane of the LTO substrate. For the 36LTO/Co and 112LTO/Co samples, polycrystalline hcp-Co was identified when the thickness exceeded approximately 10 nm, and their K u values were lower than those of the 42LTO/Co sample. These results indicate that the K u induced in the Co thin films is strongly influenced by the crystal structure of Co grown on the respective LTO substrates.