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.
Highlights
Kinetics of 90u domain wall motions and high frequency mesoscopic dielectric response in strained ferroelectrics: A phase-field simulation
The dielectric and ferroelectric behaviors of a ferroelectric are substantially determined by its domain structure and domain wall dynamics at mesoscopic level
A tensile strain favors the parallel domains but suppresses the kinetics of the 906 domain wall motion driven by electric field, while the compressive strain results in the opposite behaviors
Summary
Kinetics of 90u domain wall motions and high frequency mesoscopic dielectric response in strained ferroelectrics: A phase-field simulation. These strain effects raise particular attention to FE thin films deposited on rigid substrates, in which the induced strain can be controlled due to the lattice mismatch of the substrates with the films It allows the performance improvement of the FE thin films by means of ‘strain-engineering’ the FE domains in the mesoscopic level. Epitaxial BaTiO3 and PbTiO3 thin films deposited on substrates such as SrTiO3, LaAlO3, and MgO, are often explored for fundamental understanding and for potential applications, while textured polycrystalline films are investigated These thin films offer regular twin-like (stripe-like) 90u-domain structure in coexistence with 180u-domains due to the intrinsic ferroelastic effects. The substrate induced strain imposes a competitive or coherent coupling with the internal ferroelastic strain in the films, making the domain structure and domain wall motion complicated
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