Uniaxial magnetic anisotropy in cobalt films induced by oblique deposition of an ultrathin cobalt underlayer

Abstract

The in-plane magnetization of a series of 30 Å polycrystalline cobalt films on Si(111) substrates was investigated as a function of deposition angle. The films exhibited a growth-induced uniaxial magnetic anisotropy with an easy axis of magnetization that is initially perpendicular to the adatom flux direction but rotates to parallel to the deposition direction for an oblique incidence of 75°. The coercivity increased steadily for incidence angles above 30° from a value of 15 to 270 Oe at 75° depositions. A new technique to induce the uniaxial anisotropy onto a cobalt film deposited at normal incidence with the use of a cobalt underlayer deposited at oblique incidence was demonstrated. An underlayer film of 6 Å cobalt deposited at 83° induced an observed coercivity of 375 Oe in a 30 Å cobalt film.