Multi-layer films of NiO on α-Fe2O3 were prepared by means of pulsed laser ablation. Interdiffusion led to the formation of NiFe2O4 at the interfaces. Its ferrimagnetism provided a macroscopically measurable local probe signal for monitoring the admixture of antiferromagnetic NiO and α-Fe2O3. Magnetization, torque and magneto-optical measurements were performed on the multi-layer samples. Kinetically controlled (due to the incoming particle energies) and thermally activated regimes of NiFe2O4 formation were observed as a function of the substrate temperature. In the thermally activated regime, the deposition duration per layer (and therefore the temperature-dependent diffusion at the interfaces) played a crucial role in the formation of the ferrite.

N.Keller, M.Guyot, A.Das, M.Porte, R.Krishnan: Solid State Communications, 1998, 105[5], 333-7