Multiferroic BiFeO3 films: domain structure and polarization dynamics. Zavaliche, F.; Yang, S. Y.; Zhao, T.; Chu, Y. H.; Cruz, M. P.; Eom, C. B.; and Ramesh, R. PHASE TRANSITIONS, 79(12):991-1017, DEC, 2006.
doi  abstract   bibtex   
BiFeO3 simultaneously shows antiferromagnetic and ferroelectric order with high transition temperatures, i.e. T-N similar to 370 degrees C and T-C similar to 830 degrees C, respectively. Naturally, it has been inferred that coupling exists between the magnetic and ferroelectric order parameters like in the multiferroic manganites with low transition temperatures. A thorough investigation of the ferroelectric properties of BiFeO3 is therefore in line with the understanding of its multiferroic behaviour. Here, we review the ferroelectric properties of epitaxial (001) oriented BiFeO3 films grown by different techniques on several substrates. Structural characterization along with ferroelectric quantitative analysis point at the high quality of the films. Emphasis is put on identifying the various polarization variants and domain dynamics under an applied bias. In these studies, to unravel the intricate ferroelectric domain structure, piezo-force microscopy scans have been taken along the principal crystallographic directions. Two cases have been analysed. First, a 600 nm thick film grown on SrTiO3 (001) with a thin SrRuO3 underlayer exhibits a mosaic domain pattern due to the presence of both up and down polarization domains. Mainly four polarization domains have been identified in this case, which correspond to two structural domains. Second, epitaxial BiFeO3 films grown on DyScO3 (110) and miscut SrTiO3 (001) with a thin SrRuO3 underlayer show stripe patterns, with mainly two down polarization domains. A single structural domain of orthorhombic SrRuO3 epitaxial underlayer induces this changes in the domain structure of BiFeO3. The suppression of up domains by changing the substrate conditions prove the possibility of ferroelectric domain engineering. The three possible polarization switching mechanisms, namely 71 and 109 degrees rotations, as well as 180 degrees rotation, have been identified by following the domain dynamics in a two-domain epitaxial BiFeO3 film. Interestingly, 180 degrees polarization reversal seems to be the most favorable switching mechanism in epitaxial films under an applied bias along [001]. The observation of both ferroelastic and ferroelectric switching processes open exciting possibilities for the optimization of BiFeO3'S ferroelectric properties and investigation of magnetoelectric coupling in epitaxial films. A recent photoemission study using linearly polarized X-rays proved the coupling between the ferroelectric and antiferromagnetic domain structures.
@article{ ISI:000243672500005,
Author = {Zavaliche, F. and Yang, S. Y. and Zhao, T. and Chu, Y. H. and Cruz, M.
   P. and Eom, C. B. and Ramesh, R.},
Title = {{Multiferroic BiFeO3 films: domain structure and polarization dynamics}},
Journal = {{PHASE TRANSITIONS}},
Year = {{2006}},
Volume = {{79}},
Number = {{12}},
Pages = {{991-1017}},
Month = {{DEC}},
Abstract = {{BiFeO3 simultaneously shows antiferromagnetic and ferroelectric order
   with high transition temperatures, i.e. T-N similar to 370 degrees C and
   T-C similar to 830 degrees C, respectively. Naturally, it has been
   inferred that coupling exists between the magnetic and ferroelectric
   order parameters like in the multiferroic manganites with low transition
   temperatures. A thorough investigation of the ferroelectric properties
   of BiFeO3 is therefore in line with the understanding of its
   multiferroic behaviour. Here, we review the ferroelectric properties of
   epitaxial (001) oriented BiFeO3 films grown by different techniques on
   several substrates. Structural characterization along with ferroelectric
   quantitative analysis point at the high quality of the films. Emphasis
   is put on identifying the various polarization variants and domain
   dynamics under an applied bias. In these studies, to unravel the
   intricate ferroelectric domain structure, piezo-force microscopy scans
   have been taken along the principal crystallographic directions. Two
   cases have been analysed. First, a 600 nm thick film grown on SrTiO3
   (001) with a thin SrRuO3 underlayer exhibits a mosaic domain pattern due
   to the presence of both up and down polarization domains. Mainly four
   polarization domains have been identified in this case, which correspond
   to two structural domains. Second, epitaxial BiFeO3 films grown on
   DyScO3 (110) and miscut SrTiO3 (001) with a thin SrRuO3 underlayer show
   stripe patterns, with mainly two down polarization domains. A single
   structural domain of orthorhombic SrRuO3 epitaxial underlayer induces
   this changes in the domain structure of BiFeO3. The suppression of up
   domains by changing the substrate conditions prove the possibility of
   ferroelectric domain engineering. The three possible polarization
   switching mechanisms, namely 71 and 109 degrees rotations, as well as
   180 degrees rotation, have been identified by following the domain
   dynamics in a two-domain epitaxial BiFeO3 film. Interestingly, 180
   degrees polarization reversal seems to be the most favorable switching
   mechanism in epitaxial films under an applied bias along {[}001]. The
   observation of both ferroelastic and ferroelectric switching processes
   open exciting possibilities for the optimization of BiFeO3'S
   ferroelectric properties and investigation of magnetoelectric coupling
   in epitaxial films. A recent photoemission study using linearly
   polarized X-rays proved the coupling between the ferroelectric and
   antiferromagnetic domain structures.}},
DOI = {{10.1080/01411590601067144}},
ISSN = {{0141-1594}},
ResearcherID-Numbers = {{Eom, Chang-Beom/I-5567-2014
   Ying-Hao, Chu/A-4204-2008}},
ORCID-Numbers = {{Ying-Hao, Chu/0000-0002-3435-9084}},
Unique-ID = {{ISI:000243672500005}},
}
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