Interfacial Diffusion And Exchange Bias In The Oxide Multilayer Zn0.7Ni0.3Fe2O4/BiFeO3/SrTiO3
Published 2012 · Chemistry
The aim of this work is to fabricate an all-oxide spin valve using multiferroic BiFeO3 as the antiferromagnetic pinning layer, in the hope that we may be able to switch magnetoresistance electrically. The proposed architecture is Zn0.7Ni0.3Fe2O4/ Sr1–xLaxTiO3/ Zn0.7Ni0.3Fe2O4/ BiFeO3/ LaNiO3/SrTiO3. We have demonstrated that such a multilayer structure can be grown epitaxially by the RF magnetron sputtering. X-ray diffraction showed that the films were indeed biaxially aligned with reasonable in-plane and out-of-plane textures, under the growth conditions optimised for achieving good ferroelectric and magnetic properties. X-ray photoelectron spectroscopy depth profiling showed that there was significant Bi diffusion across the interface if the BiFeO3 film was not stabilised in high oxygen ambience after deposition. High-resolution transmission electron microscopy showed a tidy and sharp Zn0.7Ni0.3Fe2O4/ BiFeO3 boundary for the Zn0.7Ni0.3Fe2O4 films grown at 550 °C, while for the films grown at higher temperature an irregular interface was observed. Under the optimum growth condition, a clear exchange bias was achieved at the Zn0.7Ni0.3Fe2O4/ BiFeO3 interface. Copyright © 2011 John Wiley & Sons, Ltd.