Mapping gradient-driven morphological phase transition at the conductive domain walls of strained multiferroic films

Abstract

The coupling between antiferrodistortion (AFD) and ferroelectric (FE) polarization, universal for all tilted perovskite multiferroics, is known to strongly correlate with domain wall functionalities in the materials. The intrinsic mechanisms of domain wall phenomena, especially AFD-FE coupling-induced phenomena at the domain walls, have continued to intrigue the scientific and technological communities because of the need to develop the future nano-scale electronic devices. Over the past years, theoretical studies often show controversial results, owing to the fact that they are neither sufficiently nor directly corroborated with experimental evidences. In this work, the AFD-FE coupling at uncharged 180° and 71° domain walls in BiFeO3 films are investigated by means of aberration-corrected scanning transmission electron microscopy with high resolution (HR-STEM) and rationalized by phenomenological Landau-Ginsburg-Devonshire (LGD) theory. We reveal a peculiar morphology at the AFD-FE walls, including kinks, meandering, triangle-like regions with opposite oxygen displacements and curvature near the interface. The LGD theory confirms that the tilt gradient energy induces these unusual morphology and the features would change delicately with different kinds of domain walls. Moreover, the 180° AFD-FE walls are proved to be conductive with an unexpected reduction of Fe-O-Fe bond angle, which is distinct from theoretical predictions. By exploring AFD-FE coupling at domain walls and its induced functionalities, we provide exciting evidences into the links between structural distortions and its electronic properties, which benefit a lot for fundamental understanding for domain wall functionalities as well as functional manipulations for novel nano-devices.

arXiv comment31 pages, 8 figures, 5 appendices

References in corpus (13)

• First-principles study of ferroelectric domain walls in multiferroic bismuth ferrite
• Landau Theory of Domain Wall Magnetoelectricity
• Interfacial Polarization and Pyroelectricity in Antiferrodistortive Structures Induced by a Flexoelectric Effect and Rotostriction
• Structure and spin dynamics of multiferroric BiFeO${}_3$
• Domain wall conduction in multiaxial ferroelectrics
• Conductivity of twin walls - surface junctions in ferroelastics: interplay of deformation potential, octahedral rotations, improper ferroelectricity and flexoelectric coupling
• 180 degree Ferroelectric Stripe Nanodomains in BiFeO3 Thin Films
• Anisotropic conductivity of uncharged domain walls in BiFeO3
• A Phenomenological Thermodynamic Potential for CaTiO3 Single Crystal
• Universal emergence of spatially-modulated structures induced by flexo-antiferrodistortive coupling in multiferroics
• Labyrinthine domains in ferroelectric nanoparticles: a manifestation of gradient-driven morphological transition
• Rotomagnetic coupling in fine grained multiferroic BiFeO3: Theory and experiment
• On the link between Octahedral Rotations and Conductivity in the Domain Walls of BiFeO3

Cited by in corpus (9)

• Electric Field Control of Three-Dimensional Vortex States in Core-Shell Ferroelectric Nanoparticles
• Chiral Polarization Textures Induced by the Flexoelectric Effect in Ferroelectric Nanocylinders
• Flexo-Elastic Control Factors of Domain Morphology in Core-Shell Ferroelectric Nanoparticles: Soft and Rigid Shells
• Flexo-Sensitive Polarization Vortices in Thin Ferroelectric Films
• Phenomenological description of bright domain walls in ferroelectric-antiferroelectric layered chalcogenides
• Melting of Spatially Modulated Phases in La-doped BiFeO3 at Surfaces and Surface-Domain Wall Junctions
• Mesoscopic structure of mixed type domain walls in multiaxial ferroelectrics
• Phase transitions in ferroelectric domain walls
• Control of domain states in rhombohedral PZT films via misfit strains and surface charges