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

Heterostructure $$\hbox {Ba}_0.7\hbox {Sr}_0.3\hbox {TiO}₃$$ – $$\hbox {Ni}_0.8\hbox {Zn}_0.2\hbox {Fe}₂\hbox {O}₄$$ composite thin films grown on Pt– $$\hbox {TiO}₂$$ – $$\hbox {SiO}₂$$ – $$\hbox {Si}$$ substrate were prepared by chemical solution process, where $$\hbox {Ba}_0.7\hbox {Sr}_0.3\hbox {TiO}₃$$ layer grew as top/bottom while $$\hbox {Ni}_0.8\hbox {Zn}_0.2\hbox {Fe}₂\hbox {O}₄$$ 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. In particular, an exceptionally large saturation magnetization was observed in one heterostructures film. The growth sequences of $$\hbox {Ba}_0.7\hbox {Sr}_0.3\hbox {TiO}₃$$ and $$\hbox {Ni}_0.8\hbox {Zn}_0.2\hbox {Fe}₂\hbox {O}₄$$ layers on the substrate remarkably affect the magnetic properties of the composite thin films at room temperature.