Fe3O4 thin films epitaxially growth model on TiO2-terminated SrTiO3(100)

Abstract

The advanced interface of Fe 3 O 4 /SrTiO 3 , popular in spintronic, has attracted considerable attention. Some experiments have given controversial results on the structure at the Fe 3 O 4 /SrTiO 3 (100) interface. One opinion suggests the formation of interfacial antiferromagnetic FeO layers, while another opinion suggests that are γ-Fe 2 O 3 layers. Here, we propose a theoretical model that what kind of iron oxide stacking sequence forming on the substrate depends on the substrate termination charge. We give a tentative and easy-to-understand growth model for epitaxy, which agrees with the opinion of γ-Fe 2 O 3 layers formation at the Fe 3 O 4 /SrTiO 3 (100) interface. This theoretical model agrees well with the experimental curve and gives a prediction for the different Fe ions concentration depending on thickness. The calculation results of the Fe ions concentration adjacent to the substrate surface show that there are almost no B-site Fe ions at the interface. It indicates that there are unusual electric and magnetic properties at interface. Our growth model illustrates that the possible magnetically dead layer at the interface is responsible for the decrease of the magnetization in the thin films. • This growth mode give credit to the results of interfacial ferrimagnetic γ-Fe 2 O 3 layer in Fe 3 O 4 /SrTiO 3 (100). • The theoretical model curve agrees with the experimental curve, gives prediction for the Fe ions concentration depending on thickness. • The calculation result shows there are almost no B-site Fe at interface. This indicates that there are unusual electric and magnetic properties at interface. The present growth illustrates there exists possible magnetically dead layer at the interface. • It is proposed that the growth mode and the oxidation level are determined by the TiO 2 -termination charge. • The phenomenon that magnetite film grown on SrTiO 3 (001) exhibited vertical compressive and lateral tensile strain, which contradicted the expected behavior, has been explained.