Thickness effects in barium hexaferrite films deposited by magnetron sputtering

Abstract

In this work, barium ferrite films were deposited onto sapphire substrates by radio frequency magnetron sputtering. A thin amorphous barium ferrite film of about 20 nm was deposited at low temperature as a buffer layer. Barium ferrite films with thicknesses of 100 nm, 1 μm and 8 μm have been prepared. The results show that the 8-μm-thick barium ferrite films have no cracks whereas the barium ferrite films without amorphous buffer layer break and peel off. The barium ferrite films with a thickness of 100 nm show good c-axis orientation and strong magnetic anisotropy. The c-axis orientation deteriorates, and the magnetic anisotropy disappears gradually with the increase of the thickness of the barium ferrite films. The barium ferrite films with a thickness of 8 μm orientate randomly and show magnetic isotropy. The thickness effects may be explained by the increase of the random nucleation sites.