Topological protection breakdown: a route to frustrated ferroelectricity

TL;DR

This paper introduces the Topological Breakdown Model to explain complex, metastable domain patterns in ferroelectric KTN crystals, revealing how topological protection can break down, leading to frustrated non-ergodic states.

Contribution

The study develops a new model linking topological protection breakdown to frustration in ferroelectric domain patterns, validated by experimental phase diagrams and transitions.

Findings

Validated model explains mesoscopic domain patterns

Identified sharp and broad percolative transitions

Revealed fundamental link between topological protection and frustration

Abstract

Phases manifesting topological patterns in functional systems, like ferroelectric and ferromagnetic vortex superlattices, can manifest intricate and apparently ungovernable behavior, typical of frustrated non-ergodic states with high-dimensional energy landscapes. This is also the case for potassium-tantalate-niobate (KTN) crystals. These transparent ferroelectrics manifest remarkable but little-understood metastable domain patterns at optical (micrometer and above) scales near the cubic-to-tetragonal structural phase transition. Here, we formulate the Topological Breakdown Model based on the competition between intrinsic scales of domain-domain collinear and non-collinear interactions associated with polarization-charge screening. The model is able to explain observed KTN mesoscopic domain patterns and phase diagram as a function of temperature and external electric field. Findings include a precise set of sharp and broad percolative transitions that are experimentally verified, validating our model. Our study identifies the central role played by competing topologically protected states, identifying a fundamental link between topological protection and frustration that supports a hitherto unexplored functional non-ergodic arena.