Periodicity-Doubling Cascades: Direct Observation in Ferroelastic Materials

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. TEXT (INTRODUCTION)The current interest in adaptable electronics calls for new paradigms of material systems with multiple metastable states. Functional materials with modulated phases 1 bring interesting possibilities in this direction, as long as we are able to tune the stability of these available states.Ferroic materials are good prospective candidates because the modulation can be controlled by external magnetic, electric or stress fields. In magnetic materials, the presence of competing interaction between spins can lead to commensurate or incommensurate modulated structures,

Electrically driven ferroelastic domain walls, domain wall interactions, and moving needle domains

“…We report interaction distances well beyond 25 unit cells, which amounts to typical wall distances of some 125 nm. This result agrees perfectly with recent observations by Everhardt et al [42] who reports domain wall interactions for distances of >100 nm.…”

Current vortices and magnetic fields driven by moving polar twin boundaries in ferroelastic materials

“…In ferroelectric/ferroelastic material, such as BaTiO 3 , the required thin stripes with periodic twins (similar to Fig. 3, but with larger twin spaces) have been successfully fabricated and carefully controlled 49 . Other materials like LaAlO 3 and Pb 3 (PO 4 ) 2 were equally used to control the ferroelastic domain patterns 50,51 .…”

In situ heating studies on temperature-induced phase transitions in epitaxial Hf0.5Zr0.5O2/La0.67Sr0.33MnO3 heterostructures

“…In polycrystalline TiN/doped-hafnia samples, there is no clear structural signature of a reversible ferroelectric to paraelectric phase transition obtained from comprehensive in situ high temperature x-ray diffraction (XRD) studies. 12 Third, domain wall motion and domain wallassisted transitions 13 have not been reported in these systems. 14,15 Recently, there has been a theoretical breakthrough, which suggested that, indeed, ferroelectricity in o-phase hafnia is of a different type, associated with flat phonon bands and 2D polar planes in a nonpolar matrix.…”