Single-domain multiferroic BiFeO3 films

Abstract

The strong coupling between antiferromagnetism and ferroelectricity at room temperature found in BiFeO3 generates high expectations for the design and development of technological devices with novel functionalities. However, the multi-domain nature of the material tends to nullify the properties of interest and complicates the thorough understanding of the mechanisms that are responsible for those properties. Here we report the realization of a BiFeO3 material in thin film form with single-domain behaviour in both its magnetism and ferroelectricity: the entire film shows its antiferromagnetic axis aligned along the crystallographic b axis and its ferroelectric polarization along the c axis. With this we are able to reveal that the canted ferromagnetic moment due to the Dzyaloshinskii–Moriya interaction is parallel to the a axis. Furthermore, by fabricating a Co/BiFeO3 heterostructure, we demonstrate that the ferromagnetic moment of the Co film does couple directly to the canted moment of BiFeO3.

Magnetoelectricity of CoFe2O4 and tetragonal phase BiFeO3 nanocomposites prepared by pulsed laser deposition

“…The more highly aligned ferroelectric polarization in the T-phase BFO may result in better spin alignment in the CFO phase via strain, leading to the enhancement of the magnetization 34 . An exchange coupling should also be considered, where the reorientation of ferroelectric polarization affects the antiferromagnetic spin distribution inside the BFO phase, which could influence the femimagnetic spin arrangement in the CFO 11,24,35 . Similar enhancements were observed when applying a −9V tip bias, for the [001] and ferroelectric polarizations of the T-phase BFO are actually equivalent.…”

“…Alternatively, BiFeO 3 (BFO) is the only known single phase room temperature multiferroic material. It has coexisting antiferromagnetic (Neel temperature T N ~ 643 K) and ferroelectric (Curie temperature T C ~ 1103 K) orders 10,11 , leading to a weak linear (intrinsic) ME coupling via the Dzyaloshinskii–Moriya interaction 12 . When used in a composite material, the polarization of BFO can couple to the magnetostriction of CFO, resulting in large quadratic (extrinsic) ME coupling via strain 13 .…”

Structure, Performance, and Application of BiFeO3 Nanomaterials

“…Such a high P r for BFO was firstly demonstrated, which caused a dramatic increase of research enthusiasm on BFO thin film ( Fig. 1e-h) [18,[24][25][26][27][28][29][30]. The structure of epitaxial BFO film is closely related to the thickness of the film and the epitaxial strain on different substrate.…”

“…The MPB in which rhombohedral and tetragonal phases coexist is thought to be for 0.67BFO-0.33BTO. Another solid solution of BFO formed with BiCoO 3 was also studied systematically [28,29,68,69]. Furthermore, a detailed crystal structure analysis of BiFe 1−x Co x O 3 was performed [68].…”

Pure phase BiFeO3 thin films sputtered over Si: A new route towards high magnetization

“…The BiFeO 3 (BFO) compound is one of the most studied multiferroics material, either in bulk, nanoparticles or in thin films [6]. BFO bulk materials have a g-type antiferromagnetic structure with a cycloid spin structure period of approximately 62 nm along (110) direction [7] [8]. The syn-thesis process of pure BFO is usually difficult due the bismuth volatility and the appearance of spurious phases like Bi 2 Fe 4 O 9 , Bi 25 FeO 39 , Bi 2 O 3 and Fe 2 O 3 .…”