Browsing by Author "Tanaka, A."

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Complex strain evolution of polar and magnetic order in multiferroic BiFeO3 thin films
(2018-09-21)
Chen, Zuhuang
;
Chen, Zhanghui
;
Kuo, Chang-Yang
;
Tang, Yunlong
;
Dedon, Liv R.
Electric-field control of magnetism requires deterministic control of the magnetic order and understanding of the magnetoelectric coupling in multiferroics like BiFeO3 and EuTiO3. Despite this critical need, there are few studies on the strain evolution of magnetic order in BiFeO3 films. Here, in (110)-oriented BiFeO3 films, we reveal that while the polarization structure remains relatively unaffected, strain can continuously tune the orientation of the antiferromagnetic-spin axis across a wide angular space, resulting in an unexpected deviation of the classical perpendicular relationship between the antiferromagnetic axis and the polarization. Calculations suggest that this evolution arises from a competition between the Dzyaloshinskii-Moriya interaction and single-ion anisotropy wherein the former dominates at small strains and the two are comparable at large strains. Finally, strong coupling between the BiFeO3 and the ferromagnet Co0.9Fe0.1 exists such that the magnetic anisotropy of the ferromagnet can be effectively controlled by engineering the orientation of the antiferromagnetic-spin axis.
Microscopic Origin of the Giant Ferroelectric Polarization in Tetragonal-like BiFeO(3)
(2011-09-29)
Zhang, J. X.
;
He, Q.
;
Trassin, M.
;
Luo, W.
;
Yi, D.
We report direct experimental evidence for a room-temperature, similar to 130 mu C/cm(2) ferroelectric polarization from the tetragonal-like BiFeO(3) phase. The physical origin of this remarkable enhancement of ferroelectric polarization has been investigated by a combination of x-ray absorption spectroscopy, scanning transmission electron microscopy, and first principles calculations. A large strain-induced Fe-ion displacement relative to the oxygen octahedra, combined with the contribution of Bi 6s lone pair electrons, is the mechanism driving the large ferroelectric polarization in this tetragonal-like phase.
Microscopic Origin of the Giant Ferroelectric Polarization in Tetragonal-like BiFeO3
(2011-09-29)
Zhang, J. X.
;
He, Q.
;
Trassin, M.
;
Luo, W.
;
Yi, D.
We report direct experimental evidence for a room-temperature, similar to 130 mu C/cm(2) ferroelectric polarization from the tetragonal-like BiFeO3 phase. The physical origin of this remarkable enhancement of ferroelectric polarization has been investigated by a combination of x-ray absorption spectroscopy, scanning transmission electron microscopy, and first principles calculations. A large strain-induced Fe-ion displacement relative to the oxygen octahedra, combined with the contribution of Bi 6s lone pair electrons, is the mechanism driving the large ferroelectric polarization in this tetragonal-like phase.
Single-domain multiferroic BiFeO3 films
(2016-09-01)
Kuo, C. -Y.
;
Hu, Z.
;
Yang, J. C.
;
Liao, S. -C.
;
Huang, Y. L.
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.
Strong orbital polarization in orthorhombic DyMnO(3): A combined x-ray linear dichroism and ab initio electronic structure study
(2010-05-15)
Chen, J. M.
;
Hu, Z.
;
Jeng, H. T.
;
Chin, Y. Y.
;
Lee, J. M.
We present a combined experimental and theoretical study on the Mn 3d orbital occupation in orthorhombic DyMnO(3) single crystals. We have observed a very strong polarization dependence in the Mn L(2,3) x-ray absorption spectra, indicative for a distinct anisotropic orbital occupation. Ab initio electronic-structure calculations clearly infer the existence of a strong orbital polarization in the e(g) band with a staggered d(3x2-r2)/d(3y2-r2)-type ordering pattern in the ab plane. This finding is in excellent agreement with a quantitative analyis of the spectra using the atomic multiplet cluster approach.
Strong orbital polarization in orthorhombic DyMnO3: A combined x-ray linear dichroism and ab initio electronic structure study
(2010-05-15)
Chen, J. M.
;
Hu, Z.
;
Jeng, H. T.
;
Chin, Y. Y.
;
Lee, J. M.
We present a combined experimental and theoretical study on the Mn 3d orbital occupation in orthorhombic DyMnO3 single crystals. We have observed a very strong polarization dependence in the Mn L-2,L-3 x-ray absorption spectra, indicative for a distinct anisotropic orbital occupation. Ab initio electronic-structure calculations clearly infer the existence of a strong orbital polarization in the e(g) band with a staggered d(3x2-r2)/d(3y2-r2)-type ordering pattern in the ab plane. This finding is in excellent agreement with a quantitative analyis of the spectra using the atomic multiplet cluster approach.