Laser-Induced Magnetic Nanostructures with Tunable Topological Properties
TL;DR: The creation and real-space observation of magnetic structures with well-defined topological properties and a lateral size as low as about 150 nm are reported, generated in a thin ferrimagnetic film by ultrashort single optical laser pulses.
Abstract: We report the creation and real-space observation of magnetic structures with well-defined topological properties and a lateral size as low as about 150 nm. They are generated in a thin ferrimagnetic film by ultrashort single optical laser pulses. Thanks to their topological properties, such structures can be classified as Skyrmions of a particular type that does not require an externally applied magnetic field for stabilization. Besides Skyrmions, we are able to generate magnetic features with topological characteristics that can be tuned by changing the laser fluence. The stability of such features is accounted for by an analytical model based on the interplay between the exchange and the magnetic dipole-dipole interactions. Skyrmions [1] are particlelike solutions of wave equations characterized by a topological index which is conserved in time and plays the important role of a quantum number for particle states in the corresponding field theory. One of the most interesting characteristics of such topological states of matter resides in the robustness that they hold with respect to perturbations and disorder. In magnetic materials, Skyrmions emerge as solitonlike excitations that cannot be traced back to the ground ferromagnetic state by continuous deformations of the local
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TL;DR: From this description, potential applications of skyrmions as information carriers in magnetic information storage and processing devices are envisaged.
Abstract: Magnetic skyrmions are particle-like nanometre-sized spin textures of topological origin found in several magnetic materials, and are characterized by a long lifetime. Skyrmions have been observed both by means of neutron scattering in momentum space and microscopy techniques in real space, and their properties include novel Hall effects, current-driven motion with ultralow current density and multiferroic behaviour. These properties can be understood from a unified viewpoint, namely the emergent electromagnetism associated with the non-coplanar spin structure of skyrmions. From this description, potential applications of skyrmions as information carriers in magnetic information storage and processing devices are envisaged.
3,132 citations
TL;DR: A review of the underlying physics of the stabilization of skyrmions at room temperature and their prospective use for spintronic applications is discussed in this paper, where the development of topological spintronics holds promise for applications in the mid-term furure, even though many challenges such as the achievement of writing, processing and reading functionalities at room-temperature and in all-electrical manipulation schemes, still lie ahead.
Abstract: Magnetic skyrmions are small swirling topological defects in the magnetization texture. Their stabilization and dynamics depend strongly on their topological properties. In most cases, they are induced by chiral interactions between atomic spins in non-centrosymmetric magnetic compounds or in thin films with broken inversion symmetry. Skyrmions can be extremely small, with diameters in the nanometre range, and behave as particles that can be moved, created and annihilated, which makes them suitable for ‘abacus’-type applications in information storage and logic technologies. Until recently, skyrmions had been observed only at low temperature and, in most cases, under large applied magnetic fields. An intense research effort has led to the identification of thin-film and multilayer structures in which skyrmions are now stable at room temperature and can be manipulated by electrical currents. The development of skyrmion-based topological spintronics holds promise for applications in the mid-term furure, even though many challenges, such as the achievement of writing, processing and reading functionalities at room temperature and in all-electrical manipulation schemes, still lie ahead. Magnetic skyrmions are topologically protected spin whirls that hold promise for applications because they can be controllably moved, created and annihilated. In this Review, the underlying physics of the stabilization of skyrmions at room temperature and their prospective use for spintronic applications are discussed.
1,462 citations
TL;DR: In this article, the authors focus on the recent advances on the route to devices prototypes, focusing on thin film and multilayered structures in which skyrmions are stabilized above room temperature and manipulated by current.
Abstract: Magnetic skyrmions are small swirling topological defects in the magnetization texture stabilized by the protection due to their topology. In most cases they are induced by chiral interactions between atomic spins existing in non-centrosymmetric magnetic compounds or in thin films in which inversion symmetry is broken by the presence of an interface. The skyrmions can be extremely small with diameters in the nanometer range and, importantly, they behave as particles that can be moved, created or annihilated, making them suitable for abacus-type applications in information storage, logic or neuro-inspired technologies. Up to the last years skyrmions were observed only at low temperature (and in most cases under large applied fields) but important efforts of research has been recently devoted to find thin film and multilayered structures in which skyrmions are stabilized above room temperature and manipulated by current. This article focuses on these recent advances on the route to devices prototypes.
1,023 citations
TL;DR: This work shows by micromagnetic simulations that the current-induced motion of skyrmions in the presence of geometrical boundaries is very different from that in an infinite plane, and shows that a single skyrMion can be created by an electric current in a simple constricted geometry comprising a plate-shaped specimen of suitable size and geometry.
Abstract: Magnetic skyrmions--vortex-like swirling spin structures with a quantized topological number that are observed in chiral magnets--are appealing for potential applications in spintronics because it is possible to control their motion with ultralow current density. To realize skyrmion-based spintronic devices, it is essential to understand skyrmion motions in confined geometries. Here we show by micromagnetic simulations that the current-induced motion of skyrmions in the presence of geometrical boundaries is very different from that in an infinite plane. In a channel of finite width, transverse confinement results in steady-state characteristics of the skyrmion velocity as a function of current that are similar to those of domain walls in ferromagnets, whereas the transient behaviour depends on the initial distance of the skyrmion from the boundary. Furthermore, we show that a single skyrmion can be created by an electric current in a simple constricted geometry comprising a plate-shaped specimen of suitable size and geometry. These findings could guide the design of skyrmion-based devices in which skyrmions are used as information carriers.
743 citations
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...In addition, it was reported that creation of skyrmion can be achieved by ultrashort single optical laser pulse [12]....
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TL;DR: In this article, the conversion, duplication and merging of isolated skyrmions with different chirality and topology are demonstrated all in one system, and they also demonstrate the conversion of another form of a Skyrmion into another form, i.e., a bimeron.
Abstract: Magnetic skyrmions, which are topological particle-like excitations in ferromagnets, have attracted a lot of attention recently. Skyrmionics is an attempt to use magnetic skyrmions as information carriers in next generation spintronic devices. Proposals of manipulations and operations of skyrmions are highly desired. Here, we show that the conversion, duplication and merging of isolated skyrmions with different chirality and topology are possible all in one system. We also demonstrate the conversion of a skyrmion into another form of a skyrmion, i.e., a bimeron. We design spin logic gates such as the AND and OR gates based on manipulations of skyrmions. These results provide important guidelines for utilizing the topology of nanoscale spin textures as information carriers in novel magnetic sensors and spin logic devices.
692 citations