Browsing by Author "Chang, Hye Jung"

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Atomically Resolved Mapping of Polarization and Electric Fields Across Ferroelectric/Oxide Interfaces by Z-contrast Imaging
(2011-06-03)
Chang, Hye Jung
;
Kalinin, Sergei V.
;
Morozovska, Anna N.
;
Huijben, Mark
;
Chu, Ying-Hao
Direct atomic displacement mapping at ferroelectric interfaces by aberration corrected scanning transmission electron microscopy (STEM) (a-STEM image, b-corresponding displacement profile) is combined with the Landau-Ginsburg-Devonshire theory to obtain the complete interface electrostatics in real space, including separate estimates for the polarization and intrinsic interface charge contributions.
Ultrathin limit and dead-layer effects in local polarization switching of BiFeO3
(2012-01-31)
Maksymovych, Peter
;
Huijben, Mark
;
Pan, Minghu
;
Jesse, Stephen
;
Balke, Nina
Using piezoresponse force microscopy in an ultrahigh vacuum, polarization switching has been detected and quantified in epitaxial BiFeO3 films from 200 to about 4 unit cells thick. Local remnant piezoresponse was utilized to probe both ferroelectric properties and effects of imperfect electrical contacts. It was found that the shape of electromechanical hysteresis loops is strongly influenced by an extrinsic dielectric gap, primarily through the suppressing effect of the depolarizing field on the spontaneous polarization in the ultrathin films. Furthermore, statistical analysis of the hysteresis loops has revealed lateral variation of the extrinsic dielectric gap with sub-10-nm resolution. Robust and reproducible ferroelectric properties of nanoscale BiFeO3 indicate its potential for nanoscale applications in information storage and spintronics.