Visibility and Apparent Size of Néel-Type Magnetic Skyrmions in Fresnel Defocus Images of Multilayer Films

Denneulin, Thibaud; Caron, Jan; Müller‐Caspary, Knut; Boulle, Olivier; Kovács, András; Dunin‐Borkowski, Rafal E.

doi:10.1017/s1431927621012927

Cited by 2 publications

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References 52 publications

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“…In the case of thicker samples beyond 300 nm, one must use a TEM setup with an acceleration voltage above 300 kV, the standard voltage for the most modern TEM instruments. Besides that, it is well known that for some magnetic textures, the Lorentz deflection forces can be completely canceled and thus give no contrast in non-tilted samples [46]; [47].…”

Section: Theoretical Analysis Of Lorentz Tem Contrastmentioning

confidence: 99%

Heliknoton in a film of cubic chiral magnet

et al. 2023

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Cubic chiral magnets exhibit a remarkable diversity of two-dimensional topological magnetic textures, including skyrmions. However, the experimental confirmation of topological states localized in all three spatial dimensions remains challenging. In this paper, we investigate a three-dimensional topological state called a heliknoton, which is a hopfion embedded into a helix or conic background. We explore the range of parameters at which the heliknoton can be stabilized under realistic conditions using micromagnetic modeling, harmonic transition state theory, and stochastic spin dynamics simulations. We present theoretical Lorentz TEM images of the heliknoton, which can be used for experimental comparison. Additionally, we discuss the stability of the heliknoton at finite temperatures and the mechanism of its collapse. Our study offers a pathway for future experimental investigations of three-dimensional topological solitons in magnetic crystals.

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Section: Theoretical Analysis Of Lorentz Tem Contrastmentioning

confidence: 99%

Heliknoton in a film of cubic chiral magnet

et al. 2023

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Magnetic bubbles with alternating chirality in domain walls

et al. 2023

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In magnetic multilayers with perpendicular anisotropy, the competition of short-range and long-range interactions gives rise to the stability of cylindrical magnetic domains, also known as magnetic bubbles. The presence of Dzyaloshinsky-Moriya interaction induced by asymmetric interfaces between magnetic and nonmagnetic layers may lead to the formation of cylindrical bubble domains with Neel-type domain walls across the whole thickness of the multilayer. Such domain walls produce no contrast in Lorentz TEM under the normal incidence of the electron beam to the film. The latter is often used as an argument for the presence of Dzyaloshinskii-Moriya interaction in the system. Here we show that in magnetic multilayers, the absence of the Lorentz TEM contrast might also have another origin. In particular, in the absence of interfacial Dzyaloshinskii-Moriya interaction and weak interlayer exchange coupling, the magnetic bubbles might have Bloch-type domain walls of alternate chirality in adjacent layers. Such domain walls also do not produce magnetic contrast in Lorentz TEM at normal incidence of the electron beam. We show that, in the absence of interlayer exchange coupling, the magnetic bubble domains with the domain walls of fixed and alternate chirality have nearly identical energies and can coexist in the same range of magnetic fields. Using the geodesic nudged elastic band method, we prove that these states are separated by finite energy barriers. Furthermore, we demonstrate that magnetic multilayers with only dipolar coupling, besides the magnetic bubbles with nontrivial topology in all layers, can accommodate solutions with trivial topology within the internal layers.

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Visibility and Apparent Size of Néel-Type Magnetic Skyrmions in Fresnel Defocus Images of Multilayer Films

Cited by 2 publications

References 52 publications

Heliknoton in a film of cubic chiral magnet

Heliknoton in a film of cubic chiral magnet

Magnetic bubbles with alternating chirality in domain walls

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