Magnetic anisotropy of sputtered FeN films due to anisotropic columnar growth of grains

FeN thin films were deposited by RF reactive diode sputtering to investigate magnetic anisotropy variation due to substrate tilt up to 45° during the film deposition. Their magnetic and morphological properties were measured by vibrating sample magnetometer (VSM), scanning electron microscope (SEM) and atomic force microscope (AFM). As the substrate tilt angle was increased, an anisotropy in the direction parallel to the substrate tilt pivot edge was induced. SEM micrographs show columnar growth of grains elongated along the substrate tilt pivot edges. The magnitude of the anisotropy was estimated by assuming the film surface roughness (“hills”) are oblate ellipsoids. The shape anisotropy thus was estimated at 26 Oe at 45° substrate tilt, which corresponded reasonably well with the measured anisotropy change of 30 Oe