Chemical nature of nanostructures of La0.6Sr0.4MnO3 on SrTiO3(1 0 0)

In order to elucidate the dynamics of coalescence of La0.6Sr0.4MnO3 nanostructures on SrTiO3(1 0 0), we have investigated the relationship between the electronic states of La0.6Sr0.4MnO3 and the surface morphology of nanostructures, by using photoelectron spectroscopy and local probe microscopy. When the La0.6Sr0.4MnO3 nanodots are heated from 700 to 800 °C, the average nanodot size increases, and the core level peaks of Mn 2p and La 3d do not change. In addition, the observed nanodot height is always 0.4 nm. Therefore, when the nanodots coalesce, they are laterally grown, maintaining the perovskite manganese structure. On the other hand, when nanowire structures are formed along the steps by heating the sample above 1000 °C, the Mn 2p peaks vanish, although the La 3d spectrum does not change. Therefore, upon this process, Mn atoms of the island dissolve into the bulk of SrTiO3(1 0 0), and consequently, the remaining species migrate to steps on the surface, resulting in the formation of step-decorated nanowire perovskite structures.