Browsing by Author "Zhan, Q."

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Conduction at domain walls in oxide multiferroics
(2009-03-01)
Seidel, J.
;
Martin, L. W.
;
He, Q.
;
Zhan, Q.
;
Chu, Y. -H.
Domain walls may play an important role in future electronic devices, given their small size as well as the fact that their location can be controlled. Here, we report the observation of room-temperature electronic conductivity at ferroelectric domain walls in the insulating multiferroic BiFeO(3). The origin and nature of the observed conductivity are probed using a combination of conductive atomic force microscopy, high-resolution transmission electron microscopy and first-principles density functional computations. Our analyses indicate that the conductivity correlates with structurally driven changes in both the electrostatic potential and the local electronic structure, which shows a decrease in the bandgap at the domain wall. Additionally, we demonstrate the potential for device applications of such conducting nanoscale features.
Self-assembled perovskite-spinel heterostructure on a highly distorted substrate
(2013-03-18)
Zhu, Y. M.
;
Ke, D.
;
Yu, R.
;
Hsieh, Y. H.
;
Liu, H. J.
The pattern configuration and interface structure in epitaxial BiFeO3-CoFe2O4 heterostructures grown on (010) pc NdGaO3 substrates have been investigated systematically by transmission electron microscopy and chemical analysis. The crystal orientation of CoFe2O4 variants was tuned to [111](CFO), while BiFeO3 kept [010](pc) matching the substrate. Triangular prism-shaped CoFe2O4 embedded in the BiFeO3 matrix grew as an equilibrium island mode with {111}(CFO) as its surfaces and interfaces. Two types of BiFeO3-CoFe2O4 orientation relationships were determined as (001)[010](BFO)//(0-22)[111](CFO) and (101)[010](BFO)//(similar to 220)[111](CFO). The results reveal that the dominant factors controlling the growth orientation of the present vertical heterostructures are surface energy anisotropy and atomic structure continuity. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4796037]