Effect of Pd Seed Layer on Magnetic Anisotropy in Co Films Evaporated at Oblique Incidence

The effect of Pd seed layer on the magnetic anisotropy in Co films evaporated at oblique incidence was investigated. The thickness of Pd was 500Å and that of Co was varied from 100 to 600Å. The substrate temperatures were -60, -30 and 20℃. Negatively large anisotropy of the squareness ratio appeared in the films prepared at low substrate temperatures -60 and -30℃ thought the anisotropy of the reflection coefficient and the magnetic anisotropy field were positive. The degree of the c-axis orientation perpendicular to the incidence plane seems to be a little large than that of parallel one. From these results, it is considered that the positive in-plane magnetic anisotropy may originate from the shape anisotropy of the columnar grains and/or magnetocrystalline anisotropy, and the anisotropy of the squareness ratio does not reflect the in-place magnetic anisotropy. In the films with negatively large anisotropy of the squareness ratio, large coercive force perpendicular to the film plane appeared. The MH loop in those films can be explained to be superposition of two loops with small and large coercive forces. We consider that the coercive force of under Co layer is small and that of over Co layer large