Polar meron lattice in strained oxide ferroelectrics

Wang, Y. J.; Feng, Yuan Ping; Zhu, Yin; Tang, Yun; Yang, Lixin; Zou, Mingjun; Geng, Wanrong; Han, Minmin; Guo, Xiangwei; Wu, Bo; L., X.

doi:10.1038/s41563-020-0694-8

Cited by 187 publications

(116 citation statements)

References 44 publications

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“…In the 180° c -c domain wall, the strain transitions smoothly from one spontaneous polarization value to the opposite one. Whereas, in the a -c domain wall, the tilted domain wall polarization causes large strains to sustain the domain patterns [ 48 ]. The broadened and highly stressed a -c domain wall has different physical properties from the smooth transition c-c domain wall, resulting in asymmetry in domain wall charge accumulation and distribution.…”

Section: Resultsmentioning

confidence: 99%

Phase Transition Effect on Ferroelectric Domain Surface Charge Dynamics in BaTiO3 Single Crystal

He¹,

Tang²,

Liu³

et al. 2021

Materials

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The ferroelectric domain surface charge dynamics after a cubic-to-tetragonal phase transition on the BaTiO3 single crystal (001) surface was directly measured through scanning probe microscopy. The captured surface potential distribution shows significant changes: the domain structures formed rapidly, but the surface potential on polarized c domain was unstable and reversed its sign after lengthy lapse; the high broad potential barrier burst at the corrugated a-c domain wall and continued to dissipate thereafter. The generation of polarization charges and the migration of surface screening charges in the surrounding environment take the main responsibility in the experiment. Furthermore, the a-c domain wall suffers large topological defects and polarity variation, resulting in domain wall broadening and stress changes. Thus, the a-c domain wall has excess energy and polarization change is inclined to assemble on it. The potential barrier decay with time after exposing to the surrounding environment also gave proof of the surface screening charge migration at surface. Thus, both domain and domain wall characteristics should be taken into account in ferroelectric application.

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Section: Resultsmentioning

confidence: 99%

Phase Transition Effect on Ferroelectric Domain Surface Charge Dynamics in BaTiO3 Single Crystal

He¹,

Tang²,

Liu³

et al. 2021

Materials

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“…This difference renders the pursuit of ferroelectric topological objects particularly challenging. To date, successful cases have been only reported in a limited number of ferroelectric film systems, including PbTiO 3 and BiFeO 3 films, where polar vortices 2,4,5 , skyrmions 3,10 , and merons 12 have been discovered. These were mainly achieved via designing mechanical and electrical boundary conditions to flatten the energy landscape of ground-state polar structures and bring about the rotation of polar vectors.…”

Section: Introductionmentioning

confidence: 99%

Oxygen vacancy-induced topological nanodomains in ultrathin ferroelectric films

et al. 2021

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Oxygen vacancy in oxide ferroelectrics can be strongly coupled to the polar order via local strain and electric fields, thus holding the capability of producing and stabilizing exotic polarization patterns. However, despite intense theoretical studies, an explicit microscopic picture to correlate the polarization pattern and the distribution of oxygen vacancies remains absent in experiments. Here we show that in a high-quality, uniaxial ferroelectric system, i.e., compressively strained BaTiO3 ultrathin films (below 10 nm), nanoscale polarization structures can be created by intentionally introducing oxygen vacancies in the film while maintaining structure integrity (namely no extended lattice defects). Using scanning transmission electron microscopy, we reveal that the nanodomain is composed of swirling electric dipoles in the vicinity of clustered oxygen vacancies. This finding opens a new path toward the creation and understanding of the long-sought topological polar objects such as vortices and skyrmions.

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“…Unlike their ferromagnetic counterpart, ferroelectrics usually exhibit strong anisotropy that favors particular polar axes, and polarization rotation rarely occurs 5 . As a result, vast majority of polar structures naturally emerging in a ferroelectric are topologically trivial, and nontrivial polar topologies such as closure-domain 6 , 7 , vortex 8 , 9 , skyrmion 10 , meron 11 , and vortex-antivortex pair 12 have only recently been observed in reduced dimensions. It is now understood that in nanostructures such as nanodisks 13 , nanorods 14 , nanodots 15 , nanoislands 16 – 20 , and nanoplates 21 , electrostatic force dominates polar crystalline anisotropy, forcing polarization rotation and thus the formation of vortex.…”

Section: Introductionmentioning

confidence: 99%

Engineering polar vortex from topologically trivial domain architecture

et al. 2021

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Topologically nontrivial polar structures are not only attractive for high-density data storage, but also for ultralow power microelectronics thanks to their exotic negative capacitance. The vast majority of polar structures emerging naturally in ferroelectrics, however, are topologically trivial, and there are enormous interests in artificially engineered polar structures possessing nontrivial topology. Here we demonstrate reconstruction of topologically trivial strip-like domain architecture into arrays of polar vortex in (PbTiO3)10/(SrTiO3)10 superlattice, accomplished by fabricating a cross-sectional lamella from the superlattice film. Using a combination of techniques for polarization mapping, atomic imaging, and three-dimensional structure visualization supported by phase field simulations, we reveal that the reconstruction relieves biaxial epitaxial strain in thin film into a uniaxial one in lamella, changing the subtle electrostatic and elastostatic energetics and providing the driving force for the polar vortex formation. The work establishes a realistic strategy for engineering polar topologies in otherwise ordinary ferroelectric superlattices.

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Polar meron lattice in strained oxide ferroelectrics

Cited by 187 publications

References 44 publications

Phase Transition Effect on Ferroelectric Domain Surface Charge Dynamics in BaTiO3 Single Crystal

Phase Transition Effect on Ferroelectric Domain Surface Charge Dynamics in BaTiO3 Single Crystal

Oxygen vacancy-induced topological nanodomains in ultrathin ferroelectric films

Engineering polar vortex from topologically trivial domain architecture

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