Temperature Dependence of the Magnetic Properties of Reactive RF Sputtered NiFeO Thin Films

NiFeO is an antiferromagnetic material, usable in hard-disk reading heads and spintronic devices. Its properties of interest in this research are the magnetic permeability and the temperature dependence of its magnetization. Reactive RF co-sputtering was used to deposit Ni_0.81Fe_0.19O_2-δ films. Films were deposited on p-type Si at different oxygen flow rates (0.7 and 1.0 sccm O₂flow). The experiment was designed to test how the oxygen flow used during deposition affects the magnetic properties of the films. Both NiO and FeO are antiferromagnetic with Neel temperatures of respectively 525 and 198 Kelvin. It is expected that Fe doping of NiO will allow to fine-tune the Neel temperature. In addition, RF-sputtered NiFe oxide samples sputtered at low oxygen flow have a residual magnetic moment caused by oxygen vacancy clusters.

Hysteresis loops and MT curves were measured with a MicroSense VSM in fields up to 2.2 tesla between 94K and 973K. The magnetic moment of the samples decreases with temperature and becomes zero below 620K (0.7 sccm) and 740K (1.0 sccm). An irreversible change of the samples was observed after temperature exposure above 773K.