Optical pump probe techniques are utilized to measure the time-resolved magneto-optical Kerr effect ͑TRMOKE͒ of a ferromagnetic iron film at room temperature in air. We focus on the interpretation of the TRMOKE signal, and find the experimental data to be consistent with a simple phenomenological model. Nonmagnetic contributions are present in the TRMOKE signal up to 100 ps after excitation. Without making further assumptions, this prevents a determination of the true magnetization dynamics. The initial magnetization does not change its direction, and within the first picoseconds there is no detectable dependence of the magnetization dynamics on the external magnetic field.

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Thin films of V 2 O 3 with thickness 4-300 nm were grown on (11 20)-oriented sapphire substrates by reactive dc magnetron sputtering. X-ray diffraction, pole figure measurements and scanning tunnelling microscopy show high crystallinity and epitaxy to the substrate with a faceted surface structure, and the absence of strain. Measurements of the electrical resistivity, scanning tunnelling and x-ray absorption spectroscopy show a metal-insulator transition near 150 K that is connected with the opening of an energy gap and a characteristic modification of the absorption spectrum at the vanadium-2p and oxygen-1s edges. These observations reveal that the V 2 O 3 (11 20) films have bulk-like properties.

Thin films of V 2 O 3 ͑1120͒ can exist in metallic and insulating phases with different magnetic properties, similar as the bulk single crystals. We have used macroscopic magnetometry and x-ray absorption spectroscopy together with magnetic circular dichroism to show that when these films are combined with thin overlayers of bcc Fe and hcp Co, this has a pronounced impact on the electronic and magnetic properties of the interfaces. While the uncovered oxide is metallic at room temperature, both ferromagnets induce an insulating phase near the surface of the oxide, presumably due to hybridization effects at the interface. Remarkably, the electronic interaction across the interface is significantly different for the two systems. This is reflected in a magnetically "dead" atomic layer in the Fe films at the interface, a property not observed in the Co films. As a consequence the magnetic anisotropy of the two ferromagnets is dissimilar. In the antiferromagnetic phase of V 2 O 3 , at T Ͻ T N Ϸ 160 K, the hysteresis loops of the Co films exhibit a significant exchange bias; the effect is absent for Fe. The faceted surface structure of the V 2 O 3 ͑1120͒ layers induces a uniaxial magnetic anisotropy with magnetocrystalline and magnetostatic contributions in both ferromagnetic overlayers.

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