Observation of Nanoscale180°Stripe Domains in FerroelectricPbTiO3

Abstract

We report the observation of periodic 180 degrees stripe domains below the ferroelectric transition in thin films. Epitaxial PbTiO3 films of thickness d=1.6 to 42 nm on SrTiO3 substrates were studied using x-ray scattering. Upon cooling below T(C), satellites appeared around Bragg peaks indicating the presence of 180 degrees stripe domains of period Lambda=3.7 to 24 nm. The dependence of Lambda on d agrees well with theory including epitaxial strain effects, while the suppression of T(C) for thinner films is significantly larger than that expected solely from stripe domains.

Novel high-temperature ferroelectric domain morphology in PbTiO3 ultrathin films

“…This is consistent with experimental XRD results for PbTiO 3 films of similar thickness [31,32] and PbTiO 3 /SrTiO 3 superlattices [19,33,34]. Morphologically, these are LandauLifshitz domains having 90 • closure domain caps at the surface as previously observed in theoretical studies of PbTiO 3 films using interatomic potentials [11,35].…”

“…By comparing the configurational energy per unit cell when increasing the supercell dimensions and film thickness (N z ), we further demonstrate our model satisfies the Kittel scaling law, obeying a linear dependence between the optimal domain width and the square root of the thickness. For films using a s = 3.99Å at 25 K the law is satisfied for N z ≥ 5 (001)PbO layers (2 nm) which returns a periodicity of 4.0 nm in agreement with experiment [31]. For thinner films the out-of-plane components of polarisation vanishes [32] but we observe that ferroelectricity is maintained with the polarisation reorientated in-plane (a-domain).…”

Ferroelectrics at the nanoscale

“…1). Experimental evidence [15,16] suggests that this overestimates the real impact of depolarising fields, as for PbTiO 3 thin films on SrTiO 3 substrates, room temperature ferroelectricity was sustained down to three unit cells, or 1.2 nm (Fig. 2).…”

Direct evidence for ferroelectric polar distortion in ultrathin lead titanate perovskite films

“…In particular, "nanoscale" ferroelectrics have attracted considerable attention [1,2,3,4,5]. The question of the existence of a critical thickness, in other words whether or not ferroelectricity can be maintained at reduced dimensions, is amongst the most exciting topics of the field today, with very active experimental [6,7,8,9] and theoretical efforts [10,11,12].…”

“…More recently, ultrahigh vacuum scanning probe characterization based on electrostatic force microscopy was used to study ferroelectricity in barium titanate nanowires with diameters as small as 10 nm [14]. On insulating substrates, lateral periodicity was observed via x-ray diffraction in thin PbTiO 3 films down to 12Å and attributed to alternately polarized domains [7,8]. In all these studies, however, properties averaged over the complete ferroelectric structure were measured and no local information on the atomic displacements was obtained.…”