X-ray structures and magnetic properties of sputtered osmium-doped iron oxide thin films

X-ray structures and magnetic properties of sputtered osmium-doped iron oxide thin films prepared under various deposition conditions have been analyzed by x-ray diffraction and vibrating sample magnetometer techniques. Results show that the crystalline phase, macrostain, and grain size play important roles in the coercivity Hc, saturation magnetization 4πMs, and squareness S* of the films. Ferrimagnetic γ-Fe2O 3 and/or α-Fe of 400-Å grain size or less were mainly responsible for the good coercivities and magnetizations of the films, i.e., Hc=700-1000 Oe and 4πMs=4000-6000 G. A film which contained appreciable antiferromagnetic α-Fe2O3 phase had much lower Hc(=130 Oe) and 4πMs(=1000 G). Correlation between macrostrain εn, and S* has been observed where the film with large compressive strains had low S*=0.69, and those with little or zero εn gave good squareness S*=0.79-0.81.