Domain Engineering for Enhanced Ferroelectric Properties of Epitaxial (001) BiFeO Thin Films

Abstract

Two‐variant stripe domains in BiFeO3 films on miscut (001) SrTiO3 substrates exhibit square‐like, complete ferroelectric switching with low leakage current. Both the preferential distortion of BiFeO3 unit cells and the persistent step‐flow growth induced by the substrate anisotropy are the origins of the formation of the two‐variant stripe domains in (001) BiFeO3 films.

Ferroelectric annular domains in hexagonal manganites

“…There are three well-known forms of the ferroic orders in correlation with the spontaneous magnetization (ferromagnetism), the electric polarization (ferroelectricity), and the spontaneous strain (ferroelasticity), respectively. Ferroelectricity often accompanies ferroelastic strain, so ferroelectric (FE) domains tend to form in simple elongated configurations such as stripes [5,6]. On the other hand, it is also noted that the localized magnetic and FE domains have been also investigated in certain remarkable systems, e.g.…”

Epitaxial strain and electric boundary condition effects on the structural and ferroelectric properties of BiFeO3films

“…6 Furthermore, the existence of many domain variants can suppress the ferroelectric properties of BiFeO 3 . 7 Several publications reported on selection of certain domain variants by reducing the substrate symmetry, either by introduction of a high miscut angle on cubic SrTiO 3 (001) 8 or by the use of orthorhombic (110)-cut rare earth scandate substrates. 9 The rare earth scandates have a GdFeO 3 -like structure, 10 where in one orthorhombic unit cell four monoclinic distorted perovskite pseudocubes are merged [ Fig.…”

Unit cell orientation of tetragonal-like BiFeO3 thin films grown on highly miscut LaAlO3 substrates

“…For our T'-BiFeO 3 films, therefore, substrate miscut does not lead to the same type of domain engineering as reported for R'-BiFeO 3 , where a preferential ferroelectric polarization direction is induced as a consequence of substrate steps. 5 To summarize, our study on T'-BiFeO 3 films on miscut LaAlO 3 substrates (0 <  < 5) shows that the BiFeO 3 (00l)-planes tilt away from those of the substrate as predicted by geometrical arguments in the Nagai model (except at the smallest miscuts,  < 0.2, where the substrate terrace step width greatly exceeds our film thickness). Tilts as large as 1 are achieved even in 100 nm thick films; these values are strikingly larger than those earlier observed in other perovskite materials.…”

“…Thus, for a film consisting of unit cells having a non-square in-plane lattice, the degeneracy between different in-plane film-substrate alignments may be lifted in an approach referred to as domain engineering. 4,5 Furthermore, a surface step locally results in a three-dimensional clamping of the film material instead of the biaxial stress experienced elsewhere. As a consequence of the resulting non-uniform strain in the out-of-plane direction, the (00l) planes of the film may become tilted with respect to those of the substrate.…”