We investigated the magnetic properties of ultrathin magnetite films deposited directly on MgO(001) and on a Fe(001) buffer layer. In both cases the magnetite surface structure could be identified using low energy electron diffraction. The conversion electron Mössbauer spectroscopy measurements proved that, for magnetite films deposited on the Fe buffer, superparamagnetic relaxation was strongly suppressed. The effect of a Fe overlayer on the magnetite film grown directly on MgO is considerably weaker. Longitudinal Kerr magnetometry indicated the presence of the ferromagnetic interfacial coupling between Fe and magnetite films. We conclude that the density of antiphase boundaries for films grown on the Fe buffer is lower than that of Fe 3 O 4 /MgO films.

We report on the study of epitaxial Fe/Cr trilayers with a Cr thickness of 8 nm grown at different temperatures. We show that it is possible to produce systems that exhibit interlayer exchange coupling above room temperature, while being uncoupled at lower temperatures. Through perturbed angular correlation measurements, this macroscopic effect is identified as a direct result of the growth induced characteristics of the antiferromagnetic spin density wave ordering in the Cr spacer.

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We report on the influence of strain on the magnetic properties of thin Cr͑001͒ layers in the Fe/Cr/Fe͑001͒ trilayers. The epitaxial strain in the Cr layer is measured via channeling Rutherford backscattering spectroscopy and x-ray diffraction spectroscopy. The magnetic properties of the Cr spacer layer are probed via perturbed angular correlation spectroscopy on the 111 In͑ 111 Cd͒ radioactive probe. The results indicate that the strain in the Cr spacer layer influences its Néel temperature, the orientation of the magnetic moments, and the strength of the magnetic hyperfine field on the diamagnetic 111 Cd probe.

We report on the modified magnetic properties of an epitaxial Fe/ Cr/ Fe trilayer when it is cooled in an applied magnetic field. Magnetization measurements are carried out to investigate the dependence of the field-cooling effect on the magnetic field strength and on the temperature. Perturbed angular correlation experiments are performed to study the microscopic origin of the field-cooling effect.