材料期刊网

The Fe/BaTiO3 thin-film layered structure is a prototype of charge-mediated composite multiferroics, which is a promising but challenging route to achieve a sizable magnetoelectric effect. The real structure of the interface between the ferromagnetic Fe and ferroelectric BaTiO3 layers is crucial. In this paper, epitaxial Fe layers were successfully grown on top of BaTiO3 layers by carefully controlling the pulsed laser deposition and magnetron sputtering procedures. A detailed study of interfacial structure and defects at the Fe/BaTiO3 interface was carried out by transmission electron microscopy (TEM). Electron diffraction patterns and diffraction contrast images reveal a definite epitaxial relationship between Fe and BaTiO3 (001) films and a semi-coherent interface with nearly periodic interfacial dislocations. Based on high-resolution TEM images from both [010] and [110] direction observations, the interfacial dislocations were found to be partial with Burgers vectors 1/2 alpha < 100 > and line directions of < 010 >. By employing high-resolution Z-contrast imaging, the positions of individual atoms columns were resolved. The formation mechanism of interfacial dislocations was proposed in terms of geometrical models of the interface structure. On the basis of the remaining strain analysis in each layer, the effects of both BaTiO3 thickness and the SrTiO3 substrates on the density of the interface defects were discussed.