Multiferroic materials, which offer the possibility of manipulating the magnetic state by an electric field or vice versa, are of great current interest. In this work, we demonstrate the first ...observation of electrical control of antiferromagnetic domain structure in a single-phase multiferroic material at room temperature. High-resolution images of both antiferromagnetic and ferroelectric domain structures of (001)-oriented multiferroic BiFeO3 films revealed a clear domain correlation, indicating a strong coupling between the two types of order. The ferroelectric structure was measured using piezo force microscopy, whereas X-ray photoemission electron microscopy as well as its temperature dependence was used to detect the antiferromagnetic configuration. Antiferromagnetic domain switching induced by ferroelectric polarization switching was observed, in agreement with theoretical predictions.
We demonstrate the room-temperature control of magnetization reversal with an electric field in an epitaxial nanostructure consisting of ferrimagnetic nanopillars embedded in a ferroelectric matrix. ...This was achieved by combining a weak, uniform magnetic field with the switching electric field to selectively switch pillars with only one magnetic configuration. On the basis of these experimental results, we propose to use an electric field to assist magnetic recording in multiferroic systems with high perpendicular magnetic anisotropy.
We present direct evidence for room-temperature magnetization reversal induced by an electric field in epitaxial ferroelectric BiFeO3−ferrimagnetic CoFe2O4 columnar nanostructures. Piezoelectric ...force microscopy and magnetic force microscopy were used to locally image the coupled piezoelectric-magnetic switching. Quantitative analyses give a perpendicular magnetoelectric susceptibility of ∼1.0 × 10-2 G cm/V. The observed effect is due to the strong elastic coupling between the two ferroic constituents as the result of the three-dimensional heteroepitaxy.
3D heteroepitaxial growth of BiFeO3‐CoFe2O4 nanostructures leads to unique morphological patterns depending on the substrate orientations. The morphologies of the BiFeO3‐CoFe2O4 nanostructures, ...estimated using the Winterbottom construction (see figure), are dependent on the different nucleation modes that result from the differences in surface energy anisotropy. The dimensions of the BiFeO3‐CoFe2O4 nanostructures increase as the growth temperature increases and decrease as the growth rate increases.
Stable CoFe
2O
4 nanoparticles have been obtained by co-precipitation using a microwave heating system. Transmission electron microscopy images analysis shows an agglomeration of particles with an ...average size of about 5 nm, and X-ray diffraction reveals the presence of a pure ferrite nanocrystalline phase. X-ray photoelectron spectroscopy and thermal gravimetric analysis show the presence of organic matter in the range of about 16 wt%. The magnetic response in DC fields is typical for an assembly of single-domain particles. The measured saturation magnetization is slightly larger than the bulk value, probably due to the presence of small amounts of Co and Fe. AC magnetization data indicate the presence of magnetic interactions between the nanoparticles.
A 1D periodic structure of ferroelectric domains in epitaxial BiFeO3 films is created. By careful control of the growth mechanism for the SrRuO3 bottom electrode, its in‐plane lattice parameters are ...confined by the underlying DyScO3 (110)O single‐ crystal substrate, enabling the formation of an expitaxial film of (110)O SrRuO3 with a single structural domain (see figure).
We have studied the stability of domains and domain walls in multiferroic BiFeO3 thin films using a combination of piezoelectric force microscopy and phase-field simulations. We have discovered that ...a film-substrate misfit strain may result in a drastically different thermodynamic stability of two parallel domain walls with the same orientation. A fundamental understanding of the underlying physics, the stress distribution in a domain structure, leads to a novel approach to control the ferroelastic domain stability in the multiferroic BiFeO3 system.
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