Strain-induced structural, magnetic and ferroelectric properties of heterostructure BST–NZFO nanocomposite thin film at room temperature

摘要

Heterostructure Ba$_{0.7}$Sr$_{0.3}$TiO$_3$–Ni$_{0.8}$Zn$_{0.2}$Fe$_2$O$_4$ composite thin films grown on Pt–TiO$_2$–SiO$_2$–Si substrate were prepared by chemical solution process, where Ba$_{0.7}$Sr$_{0.3}$TiO$_3$ layer grew as top/bottom while Ni$_{0.8}$Zn${0.2}$Fe$_2$O$_4$ layer grew as bottom/top. Structural characterization by X-ray diffraction and atomic force microscopy showed the similar crystal structure, different lattice parameters, large lattice strain and small grain size in heterostructures, whatever their deposition sequences. Such heterostructures present simultaneously ferromagnetic and ferroelectric responses at room temperature. Inparticular, an exceptionally large saturation magnetization was observed in one heterostructures film. The growth sequencesof Ba$_{0.7}$Sr$_{0.3}$TiO$_3$ and Ni$_{0.8}$Zn$_{0.2}$Fe$_2$O$_4$ layers on the substrate remarkably affect the magnetic properties of the compositethin films at room temperature.