TY - JOUR
T1 - Direct structural determination in ultrathin ferroelectric films by analysis of synchrotron x-ray scattering measurements
AU - Fong, D. D.
AU - Cionca, C.
AU - Yacoby, Y.
AU - Stephenson, G. B.
AU - Eastman, J. A.
AU - Fuoss, P. H.
AU - Streiffer, S. K.
AU - Thompson, Carol
AU - Clarke, R.
AU - Pindak, R.
AU - Stern, E. A.
PY - 2005
Y1 - 2005
N2 - In order to better understand ferroelectricity in thin films, it is important to explore the atomic-scale structure and the spatial distribution of polarization near the interfaces. We present sub-Ångstrom-resolution electron density maps of three ultrathin PbTiO3 films grown epitaxially on SrTiO3 (001) substrates. The maps were obtained by analysis of synchrotron x-ray scattering measurements of Bragg rod intensities using the recently developed coherent Bragg rod analysis method. A four- and a nine-unit-cell-thick film were studied at room temperature, and a nine-unit-cell-thick film was studied at 181°C. The results show that at room temperature, the PbTiO3 films are polar, monodomain, and have their polarization oriented away from the substrate. The four-unit-cell film may be the thinnest monodomain perovskite film found to be in the polar phase. At 181°C, the electron density map of the nine-unit-cell film is consistent with the presence of 180° stripe domains. In the monodomain samples, details of the atomic-scale structure of the PbTiO3 SrTiO3 interface are observed, which may provide evidence for the nature of the positive charge layer required to stabilize polarization in monodomain films.
AB - In order to better understand ferroelectricity in thin films, it is important to explore the atomic-scale structure and the spatial distribution of polarization near the interfaces. We present sub-Ångstrom-resolution electron density maps of three ultrathin PbTiO3 films grown epitaxially on SrTiO3 (001) substrates. The maps were obtained by analysis of synchrotron x-ray scattering measurements of Bragg rod intensities using the recently developed coherent Bragg rod analysis method. A four- and a nine-unit-cell-thick film were studied at room temperature, and a nine-unit-cell-thick film was studied at 181°C. The results show that at room temperature, the PbTiO3 films are polar, monodomain, and have their polarization oriented away from the substrate. The four-unit-cell film may be the thinnest monodomain perovskite film found to be in the polar phase. At 181°C, the electron density map of the nine-unit-cell film is consistent with the presence of 180° stripe domains. In the monodomain samples, details of the atomic-scale structure of the PbTiO3 SrTiO3 interface are observed, which may provide evidence for the nature of the positive charge layer required to stabilize polarization in monodomain films.
UR - http://www.scopus.com/inward/record.url?scp=28744441822&partnerID=8YFLogxK
U2 - 10.1103/PhysRevB.71.144112
DO - 10.1103/PhysRevB.71.144112
M3 - Article
AN - SCOPUS:28744441822
SN - 1098-0121
VL - 71
JO - Physical Review B - Condensed Matter and Materials Physics
JF - Physical Review B - Condensed Matter and Materials Physics
IS - 14
M1 - 144112
ER -