Correlations of structure and magnetism in Perovskite thin films

Abstract

The oxides, with chemical stoichiometry of the type ABO3, where A is an alkali, alkaline earth or rare earth ion and B is a transition metal ion, are called the perovskite oxides (i.e. oxides with the structure of the perovskite:CaTiO3). The perovskite family of oxides exhibit fascinating properties such as, high temperature superconductivity, colossal magnetoresistance, magnetoelectric effect, multiferroicity etc. Moreover, they also show diverse functionality with interesting phase-diagrams and have high compatibility when combined with other oxides of the same or other families The crystal structure of the perovskite oxides is shown in the Figure 1. It consists of corner connected octahedra BO6 which plays the key role in controlling the functional behavior of the perovskite oxides. Any variation in B-O-B bond-length and bond-angle alters the shape, size and connectivity of octahedra within material resulting in the wide-ranging physical and chemical properties of these oxides. Modifying their structure or combining these perovskite oxides with members of the same or different class opens up new avenues of tailoring their properties. During the last decade, a number of perovskite oxides have been combined in the form of multilayers, superlattices and composites for tuning functional properties. Some of these properties are rare or impossible to find in the constituent parent oxides. For example, LaAlO3/SrTiO3 multilayer shows superconductivity at the interface, although each of the combining material is an insulator individually [2], CaMnO3/CaRuO3 multilayer shows ferromagnetism while the parent compounds are antiferromagnetic insulator/paramagnetic metals, respectively.