Browsing by Author "Yang, Chan-Ho"

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Concurrent transition of ferroelectric and magnetic ordering near room temperature
(2011-11-01)
Ko, Kyung-Tae
;
Jung, Min Hwa
;
He, Qing
;
Lee, Jin Hong
;
Woo, Chang Su
Strong spin-lattice coupling in condensed matter gives rise to intriguing physical phenomena such as colossal magnetoresistance and giant magnetoelectric effects. The phenomenological hallmark of such a strong spin-lattice coupling is the manifestation of a large anomaly in the crystal structure at the magnetic transition temperature. Here we report that the magnetic Neel temperature of the multiferroic compound BiFeO3 is suppressed to around room temperature by heteroepitaxial misfit strain. Remarkably, the ferroelectric state undergoes a first-order transition to another ferroelectric state simultaneously with the magnetic transition temperature. Our findings provide a unique example of a concurrent magnetic and ferroelectric transition at the same temperature among proper ferroelectrics, taking a step toward room temperature magnetoelectric applications.
Nanoscale Control of Domain Architectures in BiFeO(3) Thin Films
(2009-04-01)
Chu, Ying-Hao
;
He, Qing
;
Yang, Chan-Ho
;
Yu, Pu
;
Martin, Lane W.
We demonstrate an approach to create a one-dimensional nanoscale array of domain walls in epitaxial La-substituted BiFeO(3) films. We have used a DySCO(3) (110)(o) single-crystal substrate to provide an anisotropic strain to exclude two of the possible structural variants. Furthermore, through careful control of electrostatic boundary conditions, such as the thickness of the SrRuO(3) bottom electrode to induce the self-poling effects, we can choose to obtain either 1090 or 710 one-dimensional periodic domain walls. Detailed measurements of the domain structures is shown using piezoresponse force microscopy and X-ray diffraction, which confirms that these periodic structures are the same as those suggested in previous literature.
Nanoscale Control of Domain Architectures in BiFeO3 Thin Films
(2009-04-01)
Chu, Ying-Hao
;
He, Qing
;
Yang, Chan-Ho
;
Yu, Pu
;
Martin, Lane W.
We demonstrate an approach to create a one-dimensional nanoscale array of domain walls in epitaxial La-substituted BiFeO3 films. We have used a DySCO3 (110)(o) single-crystal substrate to provide an anisotropic strain to exclude two of the possible structural variants. Furthermore, through careful control of electrostatic boundary conditions, such as the thickness of the SrRuO3 bottom electrode to induce the self-poling effects, we can choose to obtain either 1090 or 710 one-dimensional periodic domain walls. Detailed measurements of the domain structures is shown using piezoresponse force microscopy and X-ray diffraction, which confirms that these periodic structures are the same as those suggested in previous literature.