Spontaneous flexoeffect in nanoferroics

TL;DR

This paper investigates the spontaneous flexoeffect in nanoferroics, revealing how it influences phase transitions, symmetry, and physical properties in nanoscale ferroic systems through exact solutions and phenomenological modeling.

Contribution

It provides the first exact solutions for inhomogeneous displacement fields considering flexo-coupling in nanostructures, demonstrating the spontaneous flexo-effect's impact on properties and phase transitions.

Findings

Flexo-effect causes atomic displacements and symmetry changes.

It shifts phase transition temperatures and alters geometries.

Flexo-effect modifies coefficients and boundary conditions in models.

Abstract

Within the Landau-Ginsburg-Devonshire phenomenological approach we study the ferroic nanosystems properties changes caused by the flexo-effect (flexoelectric, flexomagnetic, flexoelastic) existing spontaneously due to the inhomogeneity of order parameters. Exact solution for the spatially inhomogeneous mechanical displacement vector allowing for flexo-coupling contribution was found for nanowires and thin pills. Strong influence of flexo-effect in nanorods and thin pills leads to the displacements of the atoms resulting into the unit cell symmetry changes, which lead to the phase transition temperature shift, as well as the flat geometry in radial direction transforms into the saucer-like one. The new phenomena can be considered as true manifestation of the spontaneous flexo-effect existence. It was shown that flexo-effect leads to (a) the appearance of new linear and nonlinear contribution and renormalization of coefficients before the order parameter gradient, (b) essentially influences the transition temperature, piezoelectric response and the spatial distribution of the order parameter, (c) results in renormalization of extrapolation length in the boundary conditions.