Magnetic Anisotropy and Anisotropic Electric Resistance of Cobalt Films Sputtered under an Oblique Cathode Arrangement

Magnetic uniaxial anisotropy was induced in sputtered films prepared in an oblique electrode arrangement. In the present study, cobalt films were deposited by rf-magnetron sputtering onto glass plates fixed to a cathode block inclined at 60° to the normal horizontal position. Experiments revealed that distinct uniaxial magnetic anisotropy and anisotropic electric resistivity were formed in the film plane for thinner films (<25nm), where the directions of easy magnetization and low resistivity coincided with the direction perpendicular to the sputtering beam, suggesting that these anisotropies originate from the chain structure caused by the self-shadowing effect as observed in vacuum evaporated films with the oblique incidence. With increasing thickness, these anisotropies vanished and another magnetic anisotropy originating from the shape effect due to the columnar structure arose, where the direction of easy magnetization coincided with the direction parallel to the sputtering beam.