Antiferroelectric-like Switching inside Ferroelastic Domain Walls

Area of Science:

• Materials Science
• Condensed Matter Physics
• Solid State Chemistry

Background:

• Ferroelastic materials possess switchable spontaneous strain and can be centrosymmetric.
• Domain walls in ferroelastic materials are typically polar due to flexoelectricity, arising from strain gradients.
• This flexoelectric polarization is generally not switchable by voltage, as it would require domain annihilation.

Purpose of the Study:

• To investigate whether domain wall polarization in the archetypal ferroelastic perovskite CaTiO3 is switchable.
• To determine if switchable polarization arises from biquadratic coupling or is constrained by unipolar flexoelectricity.
• To explore the role of electric fields in manipulating domain wall properties and polarization.

Main Methods:

• Utilized molecular dynamics calculations to simulate ferroelastic perovskite behavior under electric fields.
• Analyzed the effects of high electric fields on octahedral tilts and domain wall characteristics.
• Investigated polarization switching mechanisms and hysteresis loops.

Main Results:

• High electric fields suppress octahedral tilts, broaden ferroelastic domain walls, and induce switchable polarization.
• Switchable polarization occurs at a lower critical electric field within domain walls compared to the bulk.
• Polarization switching exhibits an antiferroelectric-like behavior with a distinct double hysteresis loop.

Conclusions:

• Domain wall polarization in ferroelastic perovskites can be switched, challenging the notion of unipolar flexoelectricity dominance.
• The observed switching is facilitated by biquadratic coupling and is more accessible at domain walls.
• The findings suggest potential for double-hysteresis switching in other ferroelastic perovskites, broadening their application scope.