Deposition of magnetite films by reactive sputtering of iron

Iron is sputtered reactively in an argon-oxygen glow discharge to form deposits of magnetite. Cycling the oxygen partial pressure between a low and a high value during sputtering causes deposition of alternating layers of Fe-metal and Fe
2
O
3
-oxide. Depending on the cycle length, a layered structure results or homogeneous films form. For all films pronounced magnetite peaks were found by X-ray analysis. In the case of homogeneous films only magnetite was found. The films were hard-magnetic with coercivities between 250 Oe and 550 Oe and squarenesses between 0.6 and 0.8. Magnetic recording of these films on 14-in disks yielded bit-densities of up to 6.5 kT/cm.