Kinetics of 90° domain wall motions and high frequency mesoscopic dielectric response in strained ferroelectrics: A phase-field simulation

Abstract

The dielectric and ferroelectric behaviors of a ferroelectric are substantially determined by its domain structure and domain wall dynamics at mesoscopic level. A relationship between the domain walls and high frequency mesoscopic dielectric response is highly appreciated for high frequency applications of ferroelectrics. In this work we investigate the low electric field driven motion of 90°-domain walls and the frequency-domain spectrum of dielectric permittivity in normally strained ferroelectric lattice using the phase-field simulations. It is revealed that, the high-frequency dielectric permittivity is spatially inhomogeneous and reaches the highest value on the 90°-domain walls. A tensile strain favors the parallel domains but suppresses the kinetics of the 90° domain wall motion driven by electric field, while the compressive strain results in the opposite behaviors. The physics underlying the wall motions and thus the dielectric response is associated with the long-range elastic energy. The major contribution to the dielectric response is from the polarization fluctuations on the 90°-domain walls, which are more mobile than those inside the domains. The relevance of the simulated results wth recent experiments is discussed.

Super-crystals in composite ferroelectrics

“…Further insight on the 3D domain structure requires numerical simulations based on Monte Carlo methods 42 43 and phase-field models 44 45 46 47 ; they may confirm our picture and reveal new aspects for ferroelectricity, such as polar dynamics, spontaneous long-range ordering and the role of polar strains in composite ferroelectrics with built-in compositional microstructures. In fact, the effect of the composition profile is here crucial in triggering the spontaneous formation of the macroscopic coherent structure, as it sets the typical domain size along the x direction and so rules the whole dynamic towards the equilibrium state.…”

Super-Crystals in Composite Ferroelectrics

“…Further insight on the 3D domain structure requires numerical simulations based on Monte Carlo methods 42,43 and phase-field models [44][45][46][47] ; they may confirm our picture and reveal new aspects for ferroelectricity, such as polar dynamics, spontaneous longrange ordering and the role of polar strains in composite ferroelectrics with built-in compositional microstructures. In fact, the effect of the composition profile is here crucial in triggering the spontaneous formation of the macroscopic coherent structure, as it sets the typical domain size along the x direction and so rules the whole dynamic towards the equilibrium state.…”

Superdomain dynamics in ferroelectric-ferroelastic films: Switching, jamming, and relaxation

“…The criterion for ferroelasticity originally suggested by Toledano [110] was that it is necessary and sufficient that the crystal class change at the ferroelectric transition, such that rhombohedral-rhombohedral transitions (e.g., LiNbO3) are not ferroelectric, nor are othorhombic-orthorhombic (e.g., KTiOPO4 Although the present review emphasizes net motion of domain walls, we note that oscillation of such walls is also a topic of current interest. [113][114][115] Chu et al [116] have commented that the major contribution to the dielectric response is from the polarization fluctuations on the 90°-domain walls, which are more mobile than those inside the domains. The theory [113,114] predicts a gap energy in the acoustic phonon/soft-optic mode spectrum at a few GHz, which appears to have been found in ferroelectric trissarcosine calcium chloride.…”