X-ray diffraction studies on complex metal oxides

Abstract: The ambition of this project is to assist in the pursuance of understanding the metal to insulator transition found in magnetite at ~120 K. The transition is itself very complex and links together the charge order, orbital order and lattice distortion of magnetite with its magnetic properties. To be able to research these relationships on a more advanced level, synchrotron methods are necessary. For certain experiments it is also desirable to have these thin films without an underlying substrate. The goal of this project is to separate a magnetite thin film from a magnesium oxide substrate and investigate the effects of this process on the structural quality of the film. Using X-ray diffraction methods a magnetite thin film sample is investigated and its crystal properties are characterized. As the lattice parameter of the magnesium oxide substrate is half of the thin film lattice parameter, the film is found to have very little strain. The quality of the thin film is also established to be high, although the interface between film and substrate seems to be rather rough. To separate the film from its substrate, chemical etching was attempted. The strategy was to dissolve the substrate leaving behind only the thin film. The plan was then to attach the film on a silicon nitride membrane with a hole in the middle to be able to carry out transmission experiments at a synchrotron. However, the dissolving process proved to be more difficult than expected and the film lift-off process was unsuccessful.