Texture formation and magnetic properties of RF sputtered CoCrTa/Cr longitudinal thin films

摘要

CoCrTa films of different thicknesses were RF-sputtered on 1000-AA-thick Cr underlayers. The in-plane coercivity has a maximum of 1670 Oe for 200-AA-thick CoCrTa films and then decreases to 740 Oe for 9000-AA-thick films. The in-plane squareness also decreases monotonically from 0.80 to 0.25 when the thickness of CoCrTa films increases from 100 AA to 9000 AA. By using transmission electron diffraction, it was found that CoCrTa films thinner than 400 AA have a distribution of c-axes lying mostly in the film plane or tilted by an angle of about 28 degrees with respect to the film plane. 9000-AA-thick CoCrTa films are dominated by perpendicularly oriented c-axes. Crystallographic texture change during the growth process of CoCrTa films could be responsible for the observed thickness dependence of the in-plane coercivity and squareness. TEM (transmission electron microscope) micrographs of these films show no physical voids in the grain boundaries.