Purely electrical detection of a skyrmion in constricted geometry

Hamamoto, Keita; Ezawa, Motohiko; Nagaosa, Naoto

doi:10.1063/1.4943949

Cited by 54 publications

(44 citation statements)

References 34 publications

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“…Our finding provides a method to detect the bits in such a geometry by adding detecting leads, similar to the case of skyrmions presented in Refs. 7,8 ; cf. Fig.…”

Section: Hopfion-based Racetrack Storage Devicementioning

confidence: 99%

Topological Hall signatures of magnetic hopfions

Göbel

Akosa

Tatara

et al. 2020

Phys. Rev. Research

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Magnetic hopfions are topologically protected three-dimensional solitons that are constituted by a tube which exhibits a topologically nontrivial spin texture in the cross-section profile and is closed to a torus. Here, we show that the hopfion's locally uncompensated emergent field leads to a topological Hall signature, although the topological Hall effect vanishes on the global level. The topological Hall signature is switchable by magnetic fields or electric currents and occurs independently of the anomalous and conventional Hall effects. It can therefore be exploited to electrically detect hopfions in experiments and even to distinguish them from other textures like skyrmion tubes. Furthermore, it can potentially be utilized in spintronic devices. Exemplarily, we propose a hopfion-based racetrack data storage device and simulate the electrical detection of the hopfions as carriers of information.

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“…Our finding provides a method to detect the bits in such a geometry by adding detecting leads, similar to the case of skyrmions presented in Refs. 7,8 ; cf. Fig.…”

Section: Hopfion-based Racetrack Storage Devicementioning

confidence: 99%

Topological Hall signatures of magnetic hopfions

Göbel

Akosa

Tatara

et al. 2020

Phys. Rev. Research

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“…This problem is resolved by the additional topological contribution to the Hall effect. The topological Hall effect 3,9,10,[47][48][49][50][51][52] is a hallmark of the skyrmion phase: Traversing electrons are deflected into a transverse direction, since their spins (partially) align with the non-collinear texture and a Berry phase is accumulated. The topological charge density acts like a fictitious magnetic field, called an emergent field 3 .…”

Section: Current-driven Motion Of Skyrmioniumsmentioning

confidence: 99%

Electrical writing, deleting, reading, and moving of magnetic skyrmioniums in a racetrack device

Göbel

Schäffer

Berakdar

et al. 2019

Sci Rep

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A magnetic skyrmionium (also called 2 π -skyrmion) can be understood as a skyrmion—a topologically nontrivial magnetic whirl—which is situated in the center of a second skyrmion with reversed magnetization. Here, we propose a new optoelectrical writing and deleting mechanism for skyrmioniums in thin films, as well as a reading mechanism based on the topological Hall voltage. Furthermore, we point out advantages for utilizing skyrmioniums as carriers of information in comparison to skyrmions with respect to the current-driven motion. We simulate all four constituents of an operating skyrmionium-based racetrack storage device: creation, motion, detection and deletion of bits. The existence of a skyrmionium is thereby interpreted as a ‘1’ and its absence as a ‘0’ bit.

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“…Evolution of the magnetic interactions J, D, andI (see equation (18)) as a function ofdistance, for a = -0.4 eV Åand * = m m 0.26 e (parameters for theAu(111) surface [37] used in equation (1)). (a) We use the RKKY approximation (see equations (19), (20), and(21)) and assume a maximal scattering cross section for the minority-spin channel d = p  ( ) 2 and no contribution for the majority-spin channel (d p =  ). (b) We go beyond the RKKY approximation and use the electronic structure renormalized by the presence of two impurities (equations (4) and (16)).…”

Section: Rkky Approximationmentioning

confidence: 99%

“…In order to obtain the analytical forms of J D , and I in the RKKYapproximation (equations (22), (23), and (25)), we evaluate the integrands needed in equations (19), (20), and(21) considering two regimes, positive or negative and…”

Section: Appendix a Appendix Bmentioning

confidence: 99%

“…[11][12][13][14]), a particular class of chiral spin texture, theexistence of whichwas predicted three decades ago [15,16]. These structures are believed to be interesting candidates for future information technology [17][18][19][20] since lower currents are required for their manipulation, in comparison to conventional domain walls [21,22].…”

Section: Introductionmentioning

confidence: 99%

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Chiral magnetism of magnetic adatoms generated by Rashba electrons

et al. 2017

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We investigate long-range chiral magnetic interactions among adatoms mediated by surface states spin-splitted by spin-orbit coupling. Using the Rashba model, the tensor of exchange interactions is extracted wherein a thepseudo-dipolar interaction is found, in addition tothe usual isotropic exchange interaction and the Dzyaloshinskii-Moriya interaction. We find that, despite the latter interaction, collinear magnetic states can still be stabilized by the pseudo-dipolar interaction. The interadatom distance controls the strength of these terms, which we exploit to design chiral magnetism in Fe nanostructures deposited on aAu(111) surface. We demonstrate that these magnetic interactions are related to superpositions of the out-of-plane and in-plane components of the skyrmionic magnetic waves induced by the adatoms in the surrounding electron gas. We show that, even if the interatomic distance is large, the size and shape of the nanostructures dramatically impacts on the strength of the magnetic interactions, thereby affecting the magnetic ground state. We also derive an appealing connection between the isotropic exchange interaction and the Dzyaloshinskii-Moriya interaction, which relates the latter to the first-order change of the former with respect tospin-orbit coupling. This implies that the chirality defined by the direction of the Dzyaloshinskii-Moriya vector is driven by the variation of the isotropic exchange interaction due to the spin-orbit interaction.distance, which was recently confirmed experimentally usingscanning tunneling microscopy (STM) and theoretically usingabinitio simulations based on density functional theory [8]. We note that today, besides theory, state-of-the-art STM experiments can be used to learn about the magnitude, oscillatory behavior and decay ofRKKY interactions, as demonstrated in  [28][29][30].Our goal is to address the DM interaction in an analytically tractable model and investigate its magnitude, sign and direction following a bottom-up approach, assembling nanostructures of different sizes and shapes, atom-by-atom. We are particularly interested in the long-range magnetic interactions that have been already investigated several times theoretically. For example, Imamura et al [31] considered pairs of localized spins interacting via the so-called two-dimensional Rashba gas of electrons [32,33] while Zhu et al [34] replaced the Rashba gas withthe surface of a topological insulator. We revisit the case of Rashba electrons and consider particularly the surface state of Au (111), where the Rashba spin splitting was observed experimentally [35]. 4 We report on selected nanostructures: dimers, wires, trimers, and two hexagonal structures deposited on the Au (111), where the interactions are mediated solely by the surface state. For the dimer case, we extract the analytical form of the magnetic exchange interactions tensor using the approximation of Imamura et al [31], labeled in the following RKKY approximation, without renormalizing the electronic structure of the Rashba el...

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Purely electrical detection of a skyrmion in constricted geometry

Cited by 54 publications

References 34 publications

Topological Hall signatures of magnetic hopfions

Topological Hall signatures of magnetic hopfions

Electrical writing, deleting, reading, and moving of magnetic skyrmioniums in a racetrack device

Chiral magnetism of magnetic adatoms generated by Rashba electrons

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