Effect of correlated oxide electrodes on disorder pinning and thermal roughening of ferroelectric domain walls in epitaxial PbZr\u3csub\u3e0.2\u3c/sub\u3eTi\u3csub\u3e0.8\u3c/sub\u3eO\u3csub\u3e3\u3c/sub\u3e thin films

Abstract

We report the competing effects of disorder pinning and thermal roughening on ferroelectric domain walls as a function of temperature in epitaxial PbZr0.2Ti0.8O3 thin films deposited on (001) SrTiO3 substrates buffered by three types of correlated oxide electrodes, La0.67Sr0.33MnO3, LaNiO3, and SrIrO3. Piezoresponse force microscopy studies show that the 50-nm PbZr0.2Ti0.8O3 films are uniformly polarized in the as-grown states, with the patterned domain structures persisting above 700 °C. For all three types of films, the domain wall roughness is dominated by two-dimensional (2D) random bond disorder at room temperature, and transitions to 1D thermal roughening upon heating. The roughness exponent ζ increases progressively from 0.3 to 0.5 within a temperature window that depends on the bottom conducting oxide type, from which we extracted the distribution of disorder pinning energy. We discuss the possible origins of the disorder pinning and the effect of the correlated oxide electrodes on the energy landscape of DW motion