Homotopy-Theoretic Study &amp; Atomic-Scale Observation of Vortex Domains in Hexagonal Manganites

Li, Jun; Chiang, Fu-Kuo; Chen, Zhe; Ma, Chao; Chu, Ming‐Wen; Chen, Cheng-Hsuan; Tian, Huanfang; Yang, H. X.; Li, Jianqi

doi:10.1038/srep28047

Cited by 25 publications

(18 citation statements)

References 42 publications

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“…The similarity of the two systems becomes apparent by comparing the domain patterns calculated for in h-RGaO 3 to scanning transmission electron microscopy studies on h-RMnO 3 [17,[45][46][47]. The changes in R corrugation across the neutral domain walls are in good qualitative agreement with the atomically resolved studies.…”

Section: Discussionsupporting

confidence: 58%

“…While significant progress has been made in DFT studies of materials with the h-RMnO 3 structure, including the mechanism of polarization [35], the nature of the improper ferroelectric phase transition [36,38], and the atomic scale structure at the domain walls [12,[20][21][22]37,[41][42][43][44], detailed atomistic simulations of their topologically protected meeting points [17,[45][46][47] remain elusive. To model such meeting points, a significantly larger number of atoms is required compared to domain wall studies, making traditional DFT computational approaches unfeasible.…”

Section: Introductionmentioning

confidence: 99%

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First-principles study of topologically protected vortices and ferroelectric domain walls in hexagonal YGaO3

et al. 2020

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Ferroelectric behavior on the meso-and macroscopic scale depends on the formation and dynamics of domains and controlling the domain patterns is imperative to device performance. While density functional theory (DFT) calculations have successfully described the basic properties of ferroelectric domain walls, the necessarily small cell sizes used for the calculations hampers DFT studies of complex domain patterns. Here, we simulate largescale complex ferroelectric domain patterns in ferroelectric YGaO 3 using multisite local orbitals as implemented in the DFT code CONQUEST. The multisite local orbital basis set gives similar bulk structural and electronic properties, and atomic domain wall structures and energetics as those obtained with conventional plane-wave DFT. With this basis set model, 3600-atom cells are used to simulate topologically protected vortices. The local atomic structure at the vortex cores is subtly different from the domain walls, with a lower electronic band gap suggesting enhanced local conductance at these cores.

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Section: Discussionsupporting

confidence: 58%

Section: Introductionmentioning

confidence: 99%

First-principles study of topologically protected vortices and ferroelectric domain walls in hexagonal YGaO3

et al. 2020

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“…For a practical application of the above outlined experimental approach we discuss a non-trivial example, namely the multiferroic hexagonal manganites h-RMnO 3 (R = Sc, Y, Dy-Lu), which belongs to a family of materials attracting much interest, particularly because of the observation of antiphase structural domains clamped to ferroelectric domain walls [154][155][156][157][158][159][160] (as discussed in DOI: 10.1515/PSR.2019.0014). The structural domains, when arranged in a particular phase relation forming a clover-leaf pattern, result in the appearance of structural vortices, which in turn induce magnetic vortices [161].…”

Section: Ferroelectric Polarization Mapping From High-resolution Imagesmentioning

confidence: 99%

7 Probing local order in multiferroics by transmission electron microscopy

Campanini¹,

Erni²,

Rossell³

2021

Multiferroics

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The ongoing trend toward miniaturization has led to an increased interest in the magnetoelectric effect, which could yield entirely new device concepts, such as electric field-controlled magnetic data storage. As a result, much work is being devoted to developing new robust room temperature (RT) multiferroic materials that combine ferromagnetism and ferroelectricity. However, the development of new multiferroic devices has proved unexpectedly challenging. Thus, a better understanding of the properties of multiferroic thin films and the relation with their microstructure is required to help drive multiferroic devices toward technological application. This review covers in a concise manner advanced analytical imaging methods based on (scanning) transmission electron microscopy which can potentially be used to characterize complex multiferroic materials. It consists of a first broad introduction to the topic followed by a section describing the so-called phase-contrast methods, which can be used to map the polar and magnetic order in magnetoelectric multiferroics at different spatial length scales down to atomic resolution. Section 3 is devoted to electron nanodiffraction methods. These methods allow measuring local strains, identifying crystal defects and determining crystal structures, and thus offer important possibilities for the detailed structural characterization of multiferroics in the ultrathin regime or inserted in multilayers or superlattice architectures. Thereafter, in Section 4, methods are discussed which allow for analyzing local strain, whereas in Section 5 methods are addressed which allow for measuring local polarization effects on a length scale of individual unit cells. Here, it is shown that the ferroelectric polarization can be indirectly determined from the atomic displacements measured in atomic resolution images. Finally, a brief outlook is given on newly established methods to probe the behavior of ferroelectric and magnetic domains and nanostructures during in situ heating/electrical biasing experiments. These in situ methods are just about at the launch of becoming increasingly popular, particularly in the field of magnetoelectric multiferroics, and shall contribute significantly to understanding the relationship between the domain dynamics of multiferroics and the specific microstructure of the films providing important guidance to design new devices and to predict and mitigate failures.

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“…This process leads to the trimerized tilting of MnO 5 bipyramids and corrugation of intercalated R layers while maintaining the six-fold symmetry with six crystallographically preferred domains denoted as α+, β-, γ+, α-, β+, γ-in sequence around the core [67]. These six-fold vortices are topologically protected and extremely stable under thermal perturbation and external biasing [68][69][70]. In-situ biasing in TEM is the most effective approach to study individual ferroelectric vortex and antivortex formation and inhalation and their dynamic switching behavior.…”

Section: Ferroelectric Vorticesmentioning

confidence: 99%

Perspectives on in situ electron microscopy

Zheng

Zhu

2017

Ultramicroscopy

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In situ transmission electron microscopy (TEM) with the ability to reveal materials dynamic processes with high spatial and temporal resolution has attracted significant interest. The recent advances in in situ methods, including liquid and gas sample environment, pump-probe ultrafast microscopy, nanomechanics and ferroelectric domain switching the aberration corrected electron optics as well as fast electron detector has opened new opportunities to extend the impact of in situ TEM in broad areas of research ranging from materials science to chemistry, physics and biology. In this article, we highlight the development of liquid environment electron microscopy and its applications in the study of colloidal nanoparticle growth, electrochemical processes and others; in situ study of topological vortices in ferroelectric and ferromagnetic materials. At the end, perspectives of future in situ TEM are provided.

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Homotopy-Theoretic Study & Atomic-Scale Observation of Vortex Domains in Hexagonal Manganites

Cited by 25 publications

References 42 publications

First-principles study of topologically protected vortices and ferroelectric domain walls in hexagonal YGaO3

First-principles study of topologically protected vortices and ferroelectric domain walls in hexagonal YGaO3

7 Probing local order in multiferroics by transmission electron microscopy

Perspectives on in situ electron microscopy

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