A possible mechanism of anomalous shift and asymmetric hysteresis behavior of ferroelectric thin films

Abstract

We studied theoretically the hysteresis behavior of ferroelectric thin films. The anomalous ferroelectric response is discussed by use of a bilayer model. Electrical conductivities of the films have been taken into account. To model the effects of the inhomogeneity of polarization and permittivity across the interface, the film is assumed to possess a secondary dielectric∕ferroelectric phase (a dead or passive layer) with asymmetric conductivity. This configuration is found to produce large shifting (along the field axis) and deformation of the measured hysteresis loop. This is a manifestation of the asymmetric conductivity of the material. Theoretical calculation based on this model shows that the observed phenomena of shifted and skewed hysteresis loop in ferroelectric thin films can be explained in this way.