# Periodicity doubling cascades: direct observation in ferroelastic materials

## TL;DR

This paper reports the direct observation of periodicity doubling cascades in BaTiO3, revealing a reversible pattern formation process during phase transitions in ferroelastic materials, supported by theoretical analysis.

## Contribution

It introduces the first direct experimental evidence of periodicity doubling cascades in ferroelastic phase transitions, proposing a general model for pattern formation.

## Key findings

- Sequential domain periodicity halving observed during phase transition.
- Reversible periodicity doubling with temperature increase.
- Supports a general theoretical model for pattern formation.

## Abstract

Very sensitive responses to external forces are found near phase transitions. However, phase transition dynamics and pre-equilibrium phenomena are difficult to detect and control. We have directly observed that the equilibrium domain structure following a phase transition in BaTiO3, a ferroelectric and ferroelastic material, is attained by halving of the domain periodicity, sequentially and multiple times. The process is reversible, displaying periodicity doubling as temperature is increased. This observation is backed theoretically and can explain the fingerprints of domain period multiplicity observed in other systems, strongly suggesting this as a general model for pattern formation during phase transitions in ferroelastic materials.

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Source: https://tomesphere.com/paper/1901.08801