Polarized Raman scattering of epitaxial PbTiO3 thin film with coexisting c and a domains

Effects of the orientation of ferroelectric domains on the characteristics of polarized Raman spectra were studied using an epitaxially grown PbTiO3 thin film in which the c-axis oriented domains coexist with the a-axis oriented domains on MgO (001). To obtain polarized spectra for both two distinctive c and a domains, we have employed scattering configurations in which the relevant phonon wave vector, k, is perpendicular to the c axis of the tetragonal unit cell. Compared with the mode frequencies of single-crystal PbTiO3, a softening of the E(TO) phonons was evident for both c and a domains, suggesting the presence of a strong tensile film stress. In addition to this, we observed a splitting of the degenerate "silent" mode into two distinctive B-1 and E modes in an epitaxially grown film on MgO (001). (C) 2002 American Institute of Physics.