First-Principles Approach to the Effect of c-axis Elongation of BaTiO 3 Thin Films

• Published in: Japanese Journal of Applied Physics Vol. 37; no. 2B; p. L235
• Main Authors: Tatsuo Schimizu, Tatsuo Schimizu, Takashi Kawakubo, Takashi Kawakubo
• Format: Journal Article
• Language: English
• Published: 01.02.1998
• ISSN: 0021-4922; 1347-4065
• DOI: 10.1143/JJAP.37.L235

The effect of c -axis elongation in the tetragonal phase of perovskite BaTiO 3 (BTO) thin films was investigated using the first-principles method with ultrasoft pseudopotentials. The total energy E P , with the relaxation of the internal atoms' positions R atom as a function of the lattice constant of the c -axis c , was drastically lowered by the polarization, i.e., the long-range dipole-dipole interaction, compared with the total energy E NP without the relaxation of R atom . The tensile elastic deformation in the direction of the c -axis was found to become much easier, due to the polarization. Changing of ferroelectric properties via the lattice constant c was also considered by investigating the distance between the Ti atom and the apex O atom as a function of the lattice constant c . Moreover, the polarizations were approximately estimated as a function of the lattice constant c utilizing the Born dynamical effective charge obtained by Axe for cubic BTO.