Defects in double Perovskites

Description

Out of the large group of double perovskite materials, Sr2FeMoO6 (SFMO) is investigated for various applications reaching from potential magnetic tunnel junctions to solid oxide fuel cells, since its ideal properties found in experiments and theoretical studies are promising - room temperature magnetism, half-metallicity, magneto-resistance, high ion transport, to name just a few of them. However, its successful usage in devices is still hindered due to a complex fabrication process. The properties of SFMO are very sensitive to the experimental growing conditions. Spintronic devices would for example need thin films with high spin polarization. All these features have one point in common – a strong dependence on growing conditions and, hence, on the appearance and the number of defects. We want to give an overview about important experimental and theoretical results. Together we studied for thin films of SFMO: point defects, defect complexes, interfaces, the effect of different substrates, electronic and magnetic properties of SFMO bulk, and impurity phases. Thereby, we could complement experimental studies with model calculations and first-principles calculations and, vice versa, theoretical observations by experiments. We showed that oxygen vacancies can explain the valence change of the Fe ions, and that they might increase the critical magnetic transition temperature. On the other hand, we found that biaxial strain caused by a substrate does not only have no influence on the magnetic properties of SFMO films but also allows for potential defect engineering. Compressive biaxial strain seems to reduce the number of defects like oxygen vacancies or so-called antisite disorder (swapping of Fe and Mo sites). Hence, this strain defect engineering could be one possibility to obtain purer SFMO samples and it could be also used as a concept for the fabrication process of oxides in general.

Period	28 Feb 2018
Event title	International Workshop: Benedictine Abbey of Frauenwörth
Event type	Conference
Location	GermanyShow on map