Interface and surface effects on ferroelectric nano-thin films

The effects originating from the interface or surface of a ferroelectric nano-thin film are accounted for in the phase field model devised. Two-dimensional simulations of domain structures and hysteresis loops were carried out. The simulation results show that transformation from an irregularly spaced to a regularly spaced 180° stripe domain structure occurs owing to competition and cooperation of the elastic and depolarizing energy in ferroelectric nano-thin films. This result is in agreement with recent experimental observations. The remnant polarization was found to decrease with decreasing film thickness, and the “actual” hysteresis loop, which was first studied by Bratkovsky and Levanyuk [Bratkovsky AM, Levanyuk AP. Appl Phys Lett 2006;89:253108.], was plotted to characterize the domain structures of ferroelectric nano-thin films and the imperfect screening effects of the electrodes.