Two-dimensional planar size effects in epitaxial PbTiO3 thin films

Abstract

In order to test a critical lateral dimension in two-dimensional (2D) planar ferroelectrics, epitaxial PbTiO3 thin films are patterned into discrete islands lithographically with different lateral sizes. As the pattern size decreases, the substrate clamping effect is significantly reduced and thus the misfit strain in the films could be relaxed further. Evolution of 90degrees domain structures as a function of lateral dimensions was characterized extensively by reciprocal space mapping using synchrotron x ray. As the lateral 2D planar size decreases in the PbTiO3 patterns on MgO(001), some of the a domains turned into c domains due to the relaxed tensile strain. In the PbTiO3 patterns on Pt(001)/MgO(001), on the other hand, the formation of 90degrees domains is enhanced by the reduction in compressive misfit strain. Equilibrium domain structures in the PbTiO3 thin film islands are also analyzed by the finite element simulation and found to be consistent with the experimental observation. (C) 2004 American Institute of Physics.