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Abstract

Oxide multiferroic thin films and heterostructures offer a wide range of properties originated from intrin-sic coupling between lattice strain and nanoscale magnetic/electronic ordering. La_0.9Ba_0.1MnO₃(LBM) thin-films and LBM/BaTiO₃/LBM (LBMBT) heterostructures were grown on single crystalline [100] siliconand [0001] Al₂O₃ using RF magnetron sputtering to study the effect of crystallinity and induced latticemismatch in the film on magnetic properties of deposited films and heterostructures. The thicknesses ofthe films on Al₂O₃ and Si are 70 and 145 nm, respectively, and for heterostructures are 40/30/40 nm onboth substrates. The microstructure of the films, state of strain and growth orientations was studied by XRD and microscopy techniques. Interplay of microstructure, strain and magnetic properties is furtherinvestigated. It is known that the crystal structure of substrates and imposed tensile strain affect thephysical properties; i.e. magnetic behavior of the film. The thin layer grown on Al₂O₃ substrate showsout-of-plane compressive strain, while Si substrate induces tensile strain on the deposited film. The mag-netic transition temperatures (T_c) of the LBM film on the Si and Al₂O₃ substrates are found to be 195 Kand 203 K, respectively, slightly higher than the bulk form, 185 K. The LBMBT heterostructure on Si sub-strate shows drastic decrease in magnetization due to produced defects created by diffusion of Ti ionsinto magnetic layer. Meanwhile, the T_c in LBMBTsincreases in respect to other studied single layers andheterostructure, because of higher tensile strain induced at the interfaces.