title: Interfacial-strain-induced structural and polarization evolutions in epitaxial multiferroic BiFeO3 (001) thin films.
abstract: Varying the film thickness is a precise route to tune the interfacial strain to manipulate the properties of the multiferroic materials. Here, to explore the effects of the interfacial strain on the properties of the multiferroic BiFeO3 films, we investigated thickness-dependent structural and polarization evolutions of the BiFeO3 films. The epitaxial growth with an atomic stacking sequence of BiO/TiO2 at the interface was confirmed by scanning transmission electron microscopy. Combining X-ray diffraction experiments and first-principles calculations, a thickness-dependent structural evolution was observed from a fully strained tetragonality to a partially relaxed one without any structural phase transition or rotated twins. The tetragonality (c/a) of the BiFeO3 films increases as the film thickness decreases, while the polarization is in contrast with this trend, and the size effect including the depolarization field plays a crucial role in this contradiction in thinner films. These findings offer an alternative strategy to manipulate structural and polarization properties by tuning the interfacial strain in epitaxial multiferroic thin films.
authors.affiliation: Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences , Beijing 100190, China.
authors.forename: Haizhong
authors.initials: H
authors.lastname: Guo
authors.forename: Ruiqiang
authors.initials: R
authors.lastname: Zhao
authors.forename: Kui-Juan
authors.initials: KJ
authors.lastname: Jin
authors.forename: Lin
authors.initials: L
authors.lastname: Gu
authors.forename: Dongdong
authors.initials: D
authors.lastname: Xiao
authors.forename: Zhenzhong
authors.initials: Z
authors.lastname: Yang
authors.forename: Xiaolong
authors.initials: X
authors.lastname: Li
authors.forename: Le
authors.initials: L
authors.lastname: Wang
authors.forename: Xu
authors.initials: X
authors.lastname: He
authors.forename: Junxing
authors.initials: J
authors.lastname: Gu
authors.forename: Qian
authors.initials: Q
authors.lastname: Wan
authors.forename: Can
authors.initials: C
authors.lastname: Wang
authors.forename: Huibin
authors.initials: H
authors.lastname: Lu
authors.forename: Chen
authors.initials: C
authors.lastname: Ge
authors.forename: Meng
authors.initials: M
authors.lastname: He
authors.forename: Guozhen
authors.initials: G
authors.lastname: Yang
keywords: BiFeO3 thin films; interfacial strain; polarization evolution; structural evolution