Ferroelectric switching in ferroelastic materials with rough surfaces

Lu, Guang‐Tao; Li, Suzhi; Ding, Xiangdong; Sun, Jun; Salje, Ekhard K. H.

doi:10.1038/s41598-019-52240-3

Cited by 25 publications

(11 citation statements)

References 40 publications

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“…The energy of avalanches in Barkhausen noise is partially released by elastic waves during acoustic emission, AE. As AE measurements have unsurpassed sensitivity they became the method of choice for the investigation of field induced changes in ferroics and are hence at the heart of current research into the dynamics of switching processes 2,13,14,[17][18][19][20][21][22]30,[32][33][34][35][36] . Here we show why some results of AE deviate from the predictions of mean field theory, MFT 14,37 .…”

Section: Acoustic Emission (Ae) Measurements Of Avalanches In Differementioning

confidence: 99%

The duration-energy-size enigma for acoustic emission

Casals

Dahmen

Gou

et al. 2021

Sci Rep

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Acoustic emission (AE) measurements of avalanches in different systems, such as domain movements in ferroics or the collapse of voids in porous materials, cannot be compared with model predictions without a detailed analysis of the AE process. In particular, most AE experiments scale the avalanche energy E, maximum amplitude Amax and duration D as E ~ Amaxx and Amax ~ Dχ with x = 2 and a poorly defined power law distribution for the duration. In contrast, simple mean field theory (MFT) predicts that x = 3 and χ = 2. The disagreement is due to details of the AE measurements: the initial acoustic strain signal of an avalanche is modified by the propagation of the acoustic wave, which is then measured by the detector. We demonstrate, by simple model simulations, that typical avalanches follow the observed AE results with x = 2 and ‘half-moon’ shapes for the cross-correlation. Furthermore, the size S of an avalanche does not always scale as the square of the maximum AE avalanche amplitude Amax as predicted by MFT but scales linearly S ~ Amax. We propose that the AE rise time reflects the atomistic avalanche time profile better than the duration of the AE signal.

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Section: Acoustic Emission (Ae) Measurements Of Avalanches In Differementioning

confidence: 99%

The duration-energy-size enigma for acoustic emission

Casals

Dahmen

Gou

et al. 2021

Sci Rep

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“…Known as domain boundary engineering, ferroelastic materials can be functionalized by designing and optimizing domain walls 1,2 . Many studies have observed that interface possess properties that do not exist in bulk, such as the superconductivity [3][4][5] , ferroelectricity 6,7 . For example, twin walls are known to be superconductive in WO 3-x 8,9 .…”

Section: Introductionmentioning

confidence: 99%

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

Ding

et al. 2020

npj Comput Mater

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Ferroelastic twin boundaries often have properties that do not exist in bulk, such as superconductivity, polarity etc. Designing and optimizing domain walls can hence functionalize ferroelastic materials. Using atomistic simulations, we report that moving domain walls have magnetic properties even when there is no magnetic element in the material. The origin of a robust magnetic signal lies in polar vortex structures induced by moving domain walls, e.g., near the tips of needle domains and near domain wall kinks. These vortices generate displacement currents, which are the origin of magnetic moments perpendicular to the vortex plane. This phenomenon is universal for ionic crystals and holds for all ferroelastic domain boundaries containing dipolar moments. The magnetic moment depends on the speed of the domain boundary, which can reach the speed of sound under strong mechanical forcing. We estimate that the magnetic moment can reach several tens of Bohr magnetons for a collective thin film of 1000 lattice planes and movements of the vortex by the speed of sound. The predicted magnetic fields in thin slabs are much larger than those observed experimentally in SrTiO3/LaAlO3 heterostructures, which may be due to weak (accidental) forcing and slow changes of the domain patterns during their experiments. The dynamical multiferroic properties of ferroelastic domain walls may have the potential to be used to construct localized magnetic memory devices in future.

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“…Another critical aspect will be a detailed understanding of the control of the walls' position and motions by means of electric or elastic stress fields. The effect of electric fields on ferroelastic wall motions 89,90 and more generally the control of domain wall dynamics (BOX 2) will be the key.…”

Section: Ferroelastics and Non-polar Materialsmentioning

confidence: 99%

Domain-wall engineering and topological defects in ferroelectric and ferroelastic materials

et al. 2020

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Ferroelectric and ferroelastic domain walls are two-dimensional (2D) topological defects with thicknesses approaching the unit cell level. When this spatial confinement is combined with observations of emergent functional properties, such as polarity in non-polar systems or electrical conductivity in otherwise insulating materials, it becomes clear that domain walls represent a new and exciting state of matter. In this review, we discuss the exotic polarisation profiles that can arise at domain walls with multiple order parameters and the different mechanisms that lead to domain wall polarity in non-polar ferroelastic materials. The emergence of energetically degenerate variants of the domain walls themselves suggests the existence of interesting quasi-1D topological defects within such walls. We also provide an overview of the general notions which have been postulated as fundamental mechanisms responsible for domain wall conduction in ferroelectrics. We then discuss the prospect of combining domain walls with transition regions observed at phase boundaries, homo-and heterointerfaces, and other quasi-2D objects, enabling emergent properties beyond those available in today's topological systems. Key points• In ferroelectrics, the emergence of a second polarisation component leads to analogues of Bloch and Néel walls. The stabilization of these walls opens the possibility for quasi-1D topological defects separating wall regions of opposite polarities.• Polar domain walls in ferroelastics rely on two mechanisms: a polarity imposed by the natural symmetry of strain-compatible domain walls, which can often be described by flexoelectric gradient coupling, and the emergence of a potentially switchable polarity when their natural symmetry is broken.• Several mechanisms are responsible for domain wall conduction in ferroelectrics: extrinsic intra-bandgap defect states, intrinsic suppression of the conduction band and intrinsic shift of the band structure induced by local electric fields.• Transition regions occurring at phase boundaries, homo-and heterointerfaces, and other quasi-2D objects probably exist at a smaller length scale, in the vicinity of domain walls, and could lead to exceptional properties and coupling phenomena.

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Ferroelectric switching in ferroelastic materials with rough surfaces

Cited by 25 publications

References 40 publications

The duration-energy-size enigma for acoustic emission

The duration-energy-size enigma for acoustic emission

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

Domain-wall engineering and topological defects in ferroelectric and ferroelastic materials

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