This thesis deals with the properties of doped perovskite manganites in the form of thin films, and with interfaces between insulating perovskites. The first question we investigate has to do with... Show moreThis thesis deals with the properties of doped perovskite manganites in the form of thin films, and with interfaces between insulating perovskites. The first question we investigate has to do with the strong reduction of the metal-insulator (MI) transition temperature when the films are strained.In particular,we investigate whether there is an influence of a change in carrier density due to strain. The data shows that the carrier density averaged over the film thickness decreases when the films become very thin. This we ascribe to the effects of the interface, and of magnetically dead layers which form close to the interface, in which charge discontinuities probably play a role. The second question, addressed in this thesis, is why the interface between two band insulators LaAlO3 and SrTiO3 is not conducting grown by sputtering, whereas many groups find conducting interfaces when growing by pulsed laser deposition (PLD). A detailed study indicates that the deposition pressure, La/Al ratio and conductivity are strongly related and play a vital role in defining the conductance of the interface. The sputter-grown non-conducting interfaces were also found to be nonmagnetic which once more emphasizes the importance of the interface oxygen stoichiometry in the mechanisms for conductance and magnetism. Show less
