We have used x-ray diffraction and Raman spectroscopy over a broad temperature range $(90\mathrm{K}⩽T⩽900\mathrm{K})$ to study the structural and dynamical behavior of ${[{\mathrm{PMN}}_{(1-x)\Lambda }∕{\left(\mathrm{Pb}\mathrm{Ti}{\mathrm{O}}_3\right)}_{x\Lambda }]}_{10}$ superlattices $(x=0.2,0.5,0.8)$ (where PMN is $\mathrm{Pb}{\mathrm{Mg}}_{1∕3}{\mathrm{Nb}}_{2∕3}{\mathrm{O}}_3$), which were epitaxially grown with a nominal wavelength $\Lambda$ of $130\mathrm{\AA }$ by pulsed laser deposition on MgO substrates buffered with ${\mathrm{La}}_{0.5}{\mathrm{Sr}}_{0.5}\mathrm{Co}{\mathrm{O}}_3$. We present a comparison of the results obtained on these superlattices with the temperature evolution of three fictitious superlattices constructed using the temperature-dependent data obtained on individual $\mathrm{Pb}\mathrm{Ti}{\mathrm{O}}_3$ and $\mathrm{Pb}{\mathrm{Mg}}_{1∕3}{\mathrm{Nb}}_{2∕3}{\mathrm{O}}_3$ epitaxial thin films. From this study, we conclude that the PMN layers in superlattices retain the structural characteristics, including the tetragonal distortion, of relaxor thin films. The $\mathrm{Pb}\mathrm{Ti}{\mathrm{O}}_3$ layers exhibit in-plane polar orientation at all temperatures. X-ray diffraction shows the stabilization, due to biaxial stress, of the ferroelectric order up to at least $873\mathrm{K}$ in the $\mathrm{Pb}\mathrm{Ti}{\mathrm{O}}_3$ layers ($T_C=763\mathrm{K}$ in bulk). The tetragonal symmetry and ferroelectric order of the $\mathrm{Pb}\mathrm{Ti}{\mathrm{O}}_3$ layers, as well as the relaxorlike behavior of the PMN layers, are confirmed by Raman spectroscopy.

• Received 14 March 2007

DOI:https://doi.org/10.1103/PhysRevB.76.014124