Polar meron-antimeron networks in strained and twisted bilayers

Bennett, Daniel; Chaudhary, Gaurav; Slager, Robert-Jan; Bousquet, Éric; Ghosez, Philippe

doi:10.1038/s41467-023-37337-8

Cited by 28 publications

(10 citation statements)

References 62 publications

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“…Vortex-oriented ferroelectric domain quadrants have been found at the interface between two distinct MBE-grown group-IV chalcogenide monolayers (MLs): an in-plane polarized ferroelectric SnTe ML and a paraelectric PbTe ML (Chang et al, 2021). Polar meron-antimeron networks have been theoretically predicted by first-principles simulations in strained and twisted bilayers of hexagonal boron nitride (Bennett et al, 2023). Polar discontinuities at headto-head and tail-to-tail domain walls in lead germanate (Pb 5 Ge 3 O 11 ) are obviated by the generation of characteristic saddle-point domain-wall morphologies with associated novel dipolar topologies due to domain bifurcation along two different axes (Tikhonov et al, 2022).…”

Section: Moving Forwardmentioning

confidence: 97%

Topological phases in polar oxide nanostructures

et al. 2023

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The past decade has witnessed dramatic progress related to various aspects of emergent topological polar textures in oxide nanostructures displaying vortices, skyrmions, merons, hopfions, dipolar waves, or labyrinthine domains, among others. For a long time, these nontrivial structures (the electric counterparts of the exotic spin textures) were not expected due to the high energy cost associated with the dipolar anisotropy: the smooth and continuous evolution of the local polarization to produce

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Section: Moving Forwardmentioning

confidence: 97%

Topological phases in polar oxide nanostructures

et al. 2023

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“…(d) A network of meron–antimeron pair is formed in twisted BN bilayer, and when a positive electric field is applied changing the winding around the boundary of the cell, one of them turns into a skyrmion or antiskyrmion while the other vanishes. Reprinted with permission 46 …”

Section: Introductionmentioning

confidence: 99%

“…Another recent study shows by first‐principles calculations that such ferroelectric domains in twisted bilayers do not just point in the out‐of‐plane direction, but also have an intricate in‐plane component. Hence the polarization vector has topologically non‐trivial winding, and the twisted bilayers form a network of merons and antimerons as displayed in Figure 2d, indicating that the polar properties of layered systems can have rich topological structures 46 …”

Section: Introductionmentioning

confidence: 99%

Theoretical designs of low‐barrier ferroelectricity

Zhong

Gao

Yang

et al. 2023

WIREs Comput Mol Sci

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Ferroelectrics with electrically switchable spontaneous polarizations can be used for information storage, where a low switching barrier is favorable to reduce the energy cost and enhance the speed for data writing. Meanwhile their robustness at working temperature should be ensured, which is a challenge for the designs of low‐barrier ferroelectrics. Here we review several types of ferroelectric mechanisms that may render both low switching barriers and room‐temperature robustness, which have been theoretically proposed in previous studies. (1) The prediction of sliding ferroelectricity with ultralow switching barriers has been experimentally confirmed in a series of van der Waals layers, which may enable convenient electrical control of various physical properties in 2D materials, like magnetic, photovoltaic, valleytronic and topological properties. (2) Hydrogen‐bonded ferroelectricity spontaneously formed by head‐to‐tail chains can be switched by proton‐transfer crossing a low barrier, and a mechanism of ultra‐high piezoelectricity utilizing the specific features of hydrogen bonding has been proposed. (3) High‐ionicity ferroelectricity induced by covalent‐like ionic bondings may entail high polarizations and low barriers during switching, which is attributed to the features of long‐range Coulomb interaction, and the long ion‐displacements crossing unitcell may give rise to unconventional ferroelectricity with quantized polarizations even in crystals of non‐ferroelectric point groups. Those low‐barrier ferroelectric mechanisms may bring in both new physics and technological advances, which are to be further explored.This article is categorized under: Structure and Mechanism > Computational Materials Science

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“…Note that additional in-plane polarizations can also arise from the out-of-plane ferroelectricity and local symmetry breaking 55 . While these effects are present in our DFT calculations, they do not create additional Hartree potential that changes the Chern numbers.…”

Section: Resultsmentioning

confidence: 99%

Polarization-driven band topology evolution in twisted MoTe2 and WSe2

Zhang,

Wang,

Liu

et al. 2024

Nat Commun

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Motivated by recent experimental observations of opposite Chern numbers in R-type twisted MoTe2 and WSe2 homobilayers, we perform large-scale density-functional-theory calculations with machine learning force fields to investigate moiré band topology across a range of twist angles in both materials. We find that the Chern numbers of the moiré frontier bands change sign as a function of twist angle, and this change is driven by the competition between moiré ferroelectricity and piezoelectricity. Our large-scale calculations, enabled by machine learning methods, reveal crucial insights into interactions across different scales in twisted bilayer systems. The interplay between atomic-level relaxation effects and moiré-scale electrostatic potential variation opens new avenues for the design of intertwined topological and correlated states, including the possibility of mimicking higher Landau level physics in the absence of magnetic field.

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Polar meron-antimeron networks in strained and twisted bilayers

Cited by 28 publications

References 62 publications

Topological phases in polar oxide nanostructures

Topological phases in polar oxide nanostructures

Theoretical designs of low‐barrier ferroelectricity

Polarization-driven band topology evolution in twisted MoTe2 and WSe2

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