%0 Journal Article
%T Optical probe of ferroelectric order in bulk and thin film perovskite titanates
%A M. R£¿ssle
%A C. N. Wang
%A P. Marsik
%A M. Yazdi-Rizi
%A K. W. Kim
%A A. Dubroka
%A I. Marozau
%A C. W. Schneider
%A J. Huml¨ª£¿ek
%A D. Baeriswyl
%A C. Bernhard
%J Physics
%D 2013
%I arXiv
%R 10.1103/PhysRevB.88.104110
%X We have measured the temperature dependence of the direct band gap, $E_g$, in SrTi$^{16}$O$_3$ and BaTiO$_3$ and related materials with quantum-paraelectric and ferroelectric properties using optical spectroscopy. We show that $E_g$ exhibits an anomalous temperature dependence with pronounced changes in the vicinity of the ferroelectric transition that can be accounted for in terms of the Fr\"ohlich electron-phonon interaction with an optical phonon mode, the so-called soft mode. We demonstrate that these characteristic changes of $E_g$ can be readily detected even in very thin films of SrTi$^{16}$O$_3$ with a strain-induced ferroelectric order. Optical spectroscopy thus can be used as a relatively simple but sensitive probe of ferroelectric order in very thin films of these titanates and probably also in subsequent multilayers and devices.
%U http://arxiv.org/abs/1309.1245v1