Fabrication and magnetic behaviour of Co film with ordered nanodot arrays

Thin cobalt films with highly ordered Co nanodot arrays have been fabricated by evaporating Co directly onto the surface of a porous anodic alumina template (PAA). The Co nanodots have diameters and heights about 80–110, 30–50 nm, respectively, arranged in a close-placed hexagonal pattern. Magnetic measurements reveal that thin Co films with nanodot arrays exhibit uniaxial magnetic anisotropy with the easy magnetization direction parallel to the surface of thin Co film, and the in-plane remanence ratio is up to 0.82, approximately twice as large as that out-of-plane. Coercivity and remanent magnetization of the films with Co dot arrays are much larger than those of unpatterned films.