Electromechanical properties of ferroelectric thin films are investigated using a two-dimensional four-state Potts model and Monte Carlo simulation. In this model, the mechanical energy density induced by strains of individual cells is included in the system Hamiltonian, in addition to the contributions from dipole-dipole and electric-field-dipole couplings. Moreover, the dipole of each individual perovskite cell is aligned to one of the four mutually perpendicular directions. Four different states of dipole orientations can be defined. The deformation of each cell is associated with its dipole orientation, resulting in two different strain states. Polarization-electric-field hysteresis loops, butterfly loops for both transverse and longitudinal strains against electric field, as well as the phase-transition temperature under different stresses and anisotropy conditions are simulated. Results are comparable to the experimental measurements.
展开▼
