Electronic properties of manganite / titanate superlattices

Here we report on the study of LaMnO$_{3}$/SrTiO$_{3}$ interfaces. While LMO in bulk is an antiferromagnetic Mott insulator and STO is a band insulator, LMO/STO superlattices exhibit ferromagnetism and in some cases metallicity, both of which can be tuned by changing the layer thicknesses. We will compare the structure, chemistry and electronic properties of LMO/STO interfaces in high quality superlattices grown by pulsed laser deposition and high O$_{2}$ pressure sputtering. The distribution of defects and electronic properties will be studied through aberration corrected electron microscopy and electron energy loss spectroscopy. PLD superlattices show two alternating interface terminations, LaO-TiO$_{2}$ and SrO-MnO$_{2}$, which cause an asymmetry in the LMO layer electronic properties. Superlattices grown by sputtering only show one termination, LaO-TiO$_{2}$, giving an overall electron doping to the system. The role of interfacial charge transfer or localization, and any changes in electronic properties due to structural relaxations induced by epitaxial strain will be examined.