Dissimilar cation migration in (001) and (110) La2/3Ca1/3MnO3 thin films

Abstract

Mixed valence manganites, such as La2/3Ca1/3MnO3 (LCMO), have been the focus of a great deal of research efforts due their ferromagnetic and metallic character that can be useful as electrodes in magnetic tunnel junctions. These devices ar based in naometric layers of ferromagnetic electrodes separated by an insulating barrier, and it is of major relevance the control of the thin film properties for the final device functionality. When grown as thin films, it has been reported that film magnetic properties are much poorer than those of their bulk counterparts [1,2]. The origin of this decrease in the magnetic properties has been ascribed to the loss of the ferromagnetic metallic mixed valence state of the Mn ions (Mn3+/4+) through the development of electronic phase separated states (ferromagnetic insulating Mn3+ and Mn4+ or non-magnetic Mn ions) along the layer [8]. Electron energy loss spectroscopy is a tool to determine the local chemistry and Mn oxidation state at the nanoscale. In this sense, several studies have been carried out in mixed valence manganites grown with (001) orientation [3—7]. Yet, very little attention has been paid to mixed valence manganites grown with other orientation, although recently (110) oriented manganite films have been reported to display enhanced magnetic properties [8].