Published online by Cambridge University Press: 19 February 2016
Effects of defect on ferroelectric stability in PbTiO3 (PTO) thinfilms have been investigated using molecular dynamics with first-principleseffective Hamiltonian. In this paper, oxygen vacancy (Vo) has been considered tostudy the hysteresis loop, spontaneous polarization as a function of filmthickness. Vo has been modeled as a charged point defect. Density functionaltheory (DFT) calculations are performed to determine the Vo-induced localizedfields (both mechanical and electrical) and the calculated DFT results are usedas inputs to molecular dynamics simulations in a large system. The strain fieldinduced by the Vo is calculated by DFT calculations and fitted by the continuumstrain modeling, and the electrostatic field is given by the superposition ofthe Vo-induced field and the external field. Vo significantly reduces thespontaneous polarization and increases the critical thickness.