Extending planar two-dimensional structures into the three-dimensional space has become a general trend in multiple disciplines, including electronics, photonics, plasmonics and magnetics. This approach provides means to modify conventional or launch novel functionalities by tailoring geometry of an object, e.g. its local curvature. In generic electronic system, curvature results appearance scalar vector geometric potentials inducing anisotropic chiral effects. specific case magnetism, even...

A magnetic energy functional is derived for an arbitrary curved thin shell on the assumption that magnetostatic effects can be reduced to effective easy-surface anisotropy; it used solving both static and dynamic problems. General solutions are obtained in limit of a strong anisotropy signs (easy-surface easy-normal cases). It shown effect curvature treated as appearance field, which aligned along surface normal case tangential anisotropy. In general, existence such field excludes strictly...

Topologically stable structures include vortices in a wide variety of matter, such as skyrmions ferro- and antiferromagnets, hedgehog point defects liquid crystals ferromagnets. These are characterized by integer-valued topological quantum numbers. In this context, closed surfaces prominent subject study they form link between fundamental mathematical theorems real physical systems. Here we perform an analysis on the topology stability equilibrium magnetization states for thin spherical...

Abstract We present a phenomenological theory of altermagnets, that captures their unique magnetization dynamics and allows modeling magnetic textures in this new phase. Focusing on the prototypical d-wave e.g., RuO 2 , we can explain intuitively characteristic lifted degeneracy magnon spectra, by emergence an effective sublattice-dependent anisotropic spin stiffness arising naturally from theory. show as consequence altermagnetic domain walls, contrast to antiferromagnets, have finite...

We show that the interaction of magnetic subsystem a curved magnet with curvature results in coupling topologically nontrivial magnetization pattern and topology object. The mechanism this is explored illustrated by an example ferromagnetic M\"obius ring, where induced domain wall appears as ground state case strong easy-normal anisotropy. For geometry, curvilinear form exchange produces additional effective Dzyaloshinskii-like term which leads to magnetochirality chirality ring. Two types...

Typically, the chiral magnetic Skyrmion is a single-state excitation. Here we propose system, where multiplet of states appears and one these can be ground one. We show that presence localized curvilinear defect drastically changes properties thin perpendicularly magnetized ferromagnetic film. For large enough amplitude discrete set equilibrium magnetization forming ladder energy levels. Each state has either zero or unit topological charge; i.e., topologically trivial multiplets generally...

The properties of magnon modes localized on a ferromagnetic skyrmion are studied. Mode eigenfrequencies display three types asymptotic behavior for large radius ${R}_{s}$, namely, ${\ensuremath{\omega}}_{0}\ensuremath{\propto}{R}_{s}^{\ensuremath{-}2}$ the breathing mode and ${\ensuremath{\omega}}_{\ensuremath{-}|\ensuremath{\mu}|}\ensuremath{\propto}{R}_{s}^{\ensuremath{-}1}$ ${\ensuremath{\omega}}_{|\ensuremath{\mu}|}\ensuremath{\propto}{R}_{s}^{\ensuremath{-}3}$ with negative positive...

It is shown that a local bend of nanowire source pinning potential for transversal head-to-head (tail-to-tail) domain wall. Eigenfrequency the wall free oscillations at and effective friction are determined as functions curvature width. The originates from curvature-induced Dzyaloshinsky-like term in exchange energy. theoretical results verified by means micromagnetic simulations case parabolic shape wire bend.

The magnetization distributions in individual soft magnetic permalloy caps on non-magnetic spherical particles with sizes ranging from 50 to 800 nm are investigated. We experimentally visualize the structures at resolution limit of x-ray circular dichroism photoelectron emission microscopy (XMCD-PEEM). By analyzing so-called tail contrast XMCD-PEEM, spatial is significantly enhanced, which allowed us explore vortices and their displacement curved surfaces. Furthermore, cap nanostructures...

The interplay of topological defects with curvature is studied for out-of-surface magnetic vortices in thin spherical nanoshells. In the case an easy-surface Heisenberg magnet it shown that underlying surface leads to a coupling between localized component vortex its delocalized in-surface structure, i.e., polarity-chirality coupling.

Abstract A magnetic nanoparticle in a vortex state is promising candidate for the information storage. One bit of corresponds to upward or downward magnetization core (vortex polarity). The dynamics driven by spin current studied theoretically. Using simple analytical model and numerical simulations, we show that nondecaying motion can be excited dc spin–polarized current, whose intensity exceeds first threshold value as result balance between spin‐torque pumping damping forces. irreversible...

We develop an approach to treat magnetic energy of a ferromagnet for arbitrary curved wires and shells on the assumption that anisotropy contribution much exceeds dipolar other weak interactions. show curvature induces two effective interactions: Dzyaloshinskii-like interaction. derive equation magnetisation dynamics propose general static solution limit case strong anisotropy. To illustrate our we consider structure in ring wire cone surface: ground states both systems essentially depend...

The domain wall motion along a helix-shaped nanowire is studied for the case of spin-current driving via Zhang-Li mechanism. analysis based on collective variable approach. Two effects are ascertained: (i) curvature results in appearance Walker limit uniaxial wire, and (ii) torsion effective shift nonadiabatic spin torque parameter $\ensuremath{\beta}$. latter effect changes considerably velocity can result negative mobility. This be also used an experimental determination...

We investigate the change of magnetic vortex states driven by curvature. The equilibrium state and magnetization reversal soft permalloy (Py, Ni${}_{80}$Fe${}_{20}$) caps on self-assembled spherical particles with diameters 100, 330, 800 nm are investigated, revealing ground for individual closely packed cap arrays. coupling between vortices is substantially reduced due to shape as apparent in a much weaker dependence process separation distance. Interestingly, remaining still sufficiently...

Dynamics of topological magnetic textures are typically induced externally by, e.g.~magnetic fields or spin/charge currents. Here, we demonstrate the effect internal-to-the-system geometry-induced motion a domain wall in curved nanostripe. Being driven by gradient curvature biaxial stripe, transversal walls acquire remarkably high velocities up to 100 m/s and do not exhibit any Walker-type speed limit. We pinpoint that inhomogeneous distribution curvature-induced Dzyaloshinskii--Moriya...

Abstract Crystals with broken inversion symmetry can host fundamentally appealing and technologically relevant periodical or localized chiral magnetic textures. The type of the texture as well its magnetochiral properties are determined by intrinsic Dzyaloshinskii-Moriya interaction (DMI), which is a material property hardly be changed. Here we put forth method to create new artificial nanoscale objects tunable from standard materials using geometrical manipulations. We introduce mesoscale...

Abstract Non-collinear magnets exhibit a rich array of dynamic properties at microwave frequencies. They can host nanometre-scale topological textures known as skyrmions, whose spin resonances are expected to be highly sensitive their local magnetic environment. Here, we report resonance study an [Ir/Fe/Co/Pt] multilayer hosting Néel skyrmions room temperature. Experiments reveal two distinct the skyrmion phase during in-plane ac excitation, with frequencies between 6–12 GHz. Complementary...

The control of the vortex state magnetic nanoparticle by ultrafast fields is studied theoretically. Using micromagnetic simulations for Permalloy nanodisk we demonstrate that core magnetization can be irreversible switched alternating field, rotating in disk plane, with frequency about 10 GHz and intensity 20 mT. We propose an analytical picture such phenomena involving creation annihilation vortex-antivortex pairs calculate phase diagram parameters leading to switching.

Modifying the curvature in magnetic nanostructures is a novel and elegant way toward tailoring physical phenomena at nanoscale, allowing one to overcome limitations apparent planar counterparts. Here, we address curvature-driven changes of static properties cylindrically curved segments with different radii curvature. The architectures are prepared by capping nonmagnetic micrometer- nanometer-sized rolled-up membranes soft-magnetic 20 nm thick permalloy (Ni(80)Fe(20)) film. A quantitative...

Magnetic helix wire is one of the most simple magnetic systems which manifest properties both curvature and torsion. There exist two equilibrium states in with easy-tangential anisotropy: a quasi-tangential magnetization distribution case relatively small curvatures torsions, an onion state opposite case. In last close to tangential one, deviations are caused by torsion curvature. Possible magnet different anisotropy directions studied theoretically. The also essentially influences spin-wave...

We theoretically predict and classify the localized modes of a skyrmion in collinear uniaxial antiferromagnet discuss how they can be excited. As central result, we find two branches eigenmodes with distinct physical properties characterized by being low or high energy excitations. The frequency dependence low-energy scales as $R_0^{-2}$ for skyrmions large radius $R_0$. Furthermore, high-energy eigenmodes, which have no direct ferromagnetic counterpart. Except breathing mode, that all...

Curvilinear nanomagnets can support magnetic skyrmions stabilized at a local curvature without any intrinsic chiral interactions. Here, we propose new mechanism to stabilize N\'{e}el skyrmion states relying on the \textit{gradient} of curvature. We illustrate our approach with an example thin film perpendicular anisotropy shaped as circular indentation. show that in addition topologically trivial ground state, there are two winding numbers $\pm 1$ and skyrmionium state number $0$. These...