Curvature and torsion effects in spin-current driven domain wall motion

The domain wall motion along a helix-shaped nanowire is studied for the case of spin-current driving via the Zhang-Li mechanism. The analysis is based on the collective variable approach. Two effects are ascertained: (i) the curvature results in the appearance of the Walker limit for a uniaxial wire, and (ii)…

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Curvature-induced domain wall pinning

A local bend of a nanowire is a source of pinning potential for a transversal head-to-head (tail-to-tail) domain wall. Eigenfrequency of the domain wall free oscillations at the pinning potential and the effective friction are determined as functions of the curvature and domain wall width. The pinning potential originates from…

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Torsion-induced effects in magnetic nanowires

A magnetic helix wire is one of the simplest magnetic systems which manifests properties of both curvature and torsion. Possible equilibrium magnetization states in the helix wire with different anisotropy directions are studied theoretically. There exist two equilibrium states in the helix wire with easy-tangential anisotropy: a quasitangential magnetization distribution…

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Spin-polarized Current and Ørsted Field

A spin-polarized electrical current leads to a variety of periodical magnetic structures in nanostripes. In the presence of the Ørsted field, which always assists an electrical current, the basic types of magnetic structures, i.e., a vortex-antivortex crystal and cross-tie domain walls, survive. The Ørsted field prevents saturation of the nanostripe…

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Möbius Ring: Magnetic and Geometrical Chiralities

Chirality symmetry breaking is a common phenomenon in the Nature. The most intriguing examples come from life sciences (chirality symmetry breaking of biological macromolecules, such as DNA) and from particle physics (e.g. neutrino helicity symmetry breaking). In magnetism, chirality is a characteristic of a number of topologically nontrivial structures, such…

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Vortex polarity switching in magnets with surface anisotropy

Vortex core reversal in magnetic particle is essentially influenced by a surface anisotropy. Under the action of a perpendicular static magnetic field the vortex core undergoes a shape deformation of pillow- or barrel-shaped type, depending on the type of the surface anisotropy. This deformation plays a key point in the…

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Curvature effects in statics and dynamics of low dimensional magnets

Nowadays there is a growing interest in studying of topological structures in curved magnetic objects such as magnetic nanowires and nanoshells. We develop an approach to treat magnetic energy of a ferromagnet for arbitrary curved wires and shells on the assumption that the anisotropy contribution greatly exceeds the dipolar and…

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Curvature Effects in Thin Magnetic Shells

The submbicron-scaled magnetism of solid state is a rapidly developing research area with a promising applied potential. Nanomagnets are often considered as elements of fast nonvolatile memory devices of high density. Up to now the theoretical study in this direction was restricted mostly by planar structures. In the current research…

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OOMMF Utilities 1.0

Object Oriented Micromagnetic Framework (OOMMF) is free, portable, extensible public domain micromagnetic program and associated tools, which was developed at the National Institute of Standards and Technology (NIST). OOMMF is very powerful and useful tool which can be thinly configured for different micromagnetic studies, but at the same time, it…

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Periodic magnetic structures generated by spin-polarized currents in nanostripes

We investigated the influence of a spin-polarized current on long ferromagnetic nanostripes. The magnetization behavior is analyzed for all range of the applied currents, up to the saturation. It is shown that the saturation current is a nonmonotonic function of the stripe width. For a stripe width increasing it approaches…

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