Residual stress and magnetic behavior of multiferroic CoFe2O4/Pb(Zr0.52Ti0.48)O3 thin films

Abstract

Multiferroic composite thin films consisting of CoFe2O4 (CFO) and Pb(Zr0.52Ti0.48)O3 (PZT) layers were deposited through a combined route of rf magnetron sputtering and sol gel on Pt(111)/TiO2/SiO2/Si substrates. The coupling effects in the bilayered thin film were studied by looking at the relationships among the crystallite orientation, magnetic behavior, and the in-plane residual stress. Phase selective residual stress analysis conducted by using x-ray method demonstrated a close correlation between the stress imposed on the PZT layer and its texture. A change in the PZT layer orientation from (1¯11) to (010) with the increasing layer thickness was observed in the multiferroic thin film as the system changes from an interface energy minimizing texture to a strain energy density minimizing texture. The CFO phase in the multiferroic thin films was preferably oriented in the (111) orientation. However, there is a change in magnetization as well as coercivity of the multiferroic thin films when the top PZT layer was varied in thickness. A close correlation between the magnetization and the in-plane stress in the CFO bottom layer imposed by the PZT film thickness was observed.