Depolarization of multidomain ferroelectric materials

Area of Science:

• Materials Science
• Condensed Matter Physics
• Solid State Physics

Background:

• Ferroelectric depolarization dynamics have been studied quasi-statically since the 1970s.
• The empirical Merz law describes polarization switching time based on electric field and activation field.
• Recent molecular dynamics simulations support domain-wall depinning as the origin of the Merz law.

Purpose of the Study:

• To experimentally investigate domain-wall depinning dynamics during ferroelectric depolarization.
• To identify a universal parameter characterizing the boundary between stable and depolarizing regimes.
• To relate the depolarization field to the activation field governing domain wall motion.

Main Methods:

• Experimental measurement of depolarization dynamics in multidomain ferroelectric materials.
• Analysis of domain-wall depinning phenomena.
• Characterization of ferroelectric properties including coercive field (E_c), dielectric constant (ε_ferro), and remanent polarization (P_r).

Main Results:

• A universal constant, P_r/(ε_0ε_ferro*E_c), approximately 15, defines the boundary between stable and depolarizing ferroelectric regimes.
• This constant is comparable across different ferroelectric materials despite orders-of-magnitude variations in their properties.
• The depolarization field was found to be similar to the activation field, indicating a transition from creep to domain-wall flow.

Conclusions:

• Domain-wall depinning is experimentally confirmed as a key mechanism in ferroelectric depolarization.
• A universal constant provides a new metric for understanding ferroelectric material behavior.
• The findings offer insights into the fundamental physics of domain wall dynamics and polarization switching.