Defects in conformal crystals: Discrete versus continuous disclination models

Meng, Qingyou; Grason, Gregory M.

doi:10.1103/physreve.104.034614

Cited by 6 publications

(1 citation statement)

References 37 publications

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“…They showed that under these conditions, a conformal vortex lattice forms spontaneously. Further studies explored conformal structures in circular geometries [49] and with different types of defects [50]. These studies focused only on the final static conformal states and did not address the dynamics during compression.…”

Section: Introductionmentioning

confidence: 99%

Spontaneous skyrmion conformal lattice and transverse motion during dc and ac compression

et al. 2023

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We use atomistic-based simulations to investigate the behavior of ferromagnetic skyrmions being continuously compressed against a rigid wall under dc and ac drives. The compressed skyrmions can be annihilated close to the wall and form a conformal crystal with both a size and a density gradient, making it distinct from conformal crystals observed previously for superconducting vortices and colloidal particles. For both dc and ac driving, the skyrmions can move transverse to the compression direction due to a combination of density and size gradients. Forces in the compression direction are converted by the Magnus force into transverse motion. Under ac driving, the amount of skyrmion annihilation is reduced and we find a skyrmion Magnus ratchet pump. We also observe shear banding in which skyrmions near the wall move up to twice as fast as skyrmions further from the wall. When we vary the magnitude of the applied drive, we find a critical current above which the skyrmions are completely annihilated during a time scale that depends on the magnitude of the drive. By varying the magnetic parameters, we find that the transverse motion is strongly dependent on the skyrmion size. Smaller skyrmions are more rigid, which interferes with the size gradient and destroys the transverse motion. We also confirm the role of the size gradient by comparing our atomistic simulations with a particle-based model, where we find that the transverse motion is only transient. Our results are relevant for applications where skyrmions encounter repulsive magnetic walls, domain walls, or interfaces.

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Section: Introductionmentioning

confidence: 99%

Spontaneous skyrmion conformal lattice and transverse motion during dc and ac compression

et al. 2023

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Circle packing on spherical caps

Amore

2024

Physics of Fluids

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We have studied the packing of congruent disks on a spherical cap, for caps of different size and number of disks, N. This problem has been considered before only in the limit cases of circle packing inside a circle and on a sphere (Tammes problem), whereas all intermediate cases are unexplored. Finding the preferred packing configurations for a domain with both curvature and border could be useful in the description of physical and biological systems (for example, colloidal suspensions or the compound eye of an insect), with potential applications in engineering and architecture (e.g., geodesic domes). We have carried out an extensive search for the densest packing configurations of congruent disks on spherical caps of selected angular widths (θmax=π/6, π/4, π/2, 3π/4, and 5π/6) and for several values of N. The numerical results obtained in the present work have been used to establish (at least qualitatively) some general features for these configurations, in particular the behavior of the packing fraction as function of the number of disks and of the angular width of the cap, or the nature of the topological defects in these configurations (it was found that as the curvature increases, the overall topological charge on the border tends to become more negative). Finally, we have studied the packing configurations for N=19, 37, 61, and 91 (hexagonal numbers) for caps ranging from the flat disk to the whole sphere, to observe the evolution (and eventual disappearance) of the curved hexagonal packing configurations while increasing the curvature.

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Phonon eigenfunctions of inhomogeneous lattices: Can you hear the shape of a cone?

Zhang

Nelson

2021

Phys. Rev. E

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Defects in conformal crystals: Discrete versus continuous disclination models

Cited by 6 publications

References 37 publications

Spontaneous skyrmion conformal lattice and transverse motion during dc and ac compression

Spontaneous skyrmion conformal lattice and transverse motion during dc and ac compression

Circle packing on spherical caps

Phonon eigenfunctions of inhomogeneous lattices: Can you hear the shape of a cone?

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