Compass-anisotropy-modulated helical states and skyrmion crystals in chiral magnets

Chen, J.P.; Zhang, Dan-Wei; Chen, Y.; Gao, Xingsen; Liu, J.-M.

doi:10.1016/j.physleta.2018.06.035

Cited by 3 publications

(5 citation statements)

References 26 publications

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“…To get the zero-temperature equilibrium state, we adopted a specific simulation scheme: the lattice was initialized as a paramagnetic phase at sufficiently high temperature, and annealed for obtaining the state at a low temperature, by using the Metropolis Monte Carlo simulation combined with overrelaxation algorithm [17,18,44]. Then the configuration was further relaxed for the equilibrium state, by solving the LLG equation under T 0 with long enough equilibration time.…”

Section: Model and Simulation Methodsmentioning

confidence: 99%

“…To explore the possible ground state for the nanomagnet of 24 × 24 square lattices at B z 0, the system was initialized from a the paramagnetic state at sufficiently high temperature T, and cooled down gradually until it reaches a very low T under B z 0, using Monte Carlo simulations with simulated annealing technique [17,18,44]. Then the system was further relaxed for the zero-temperature equilibrium state by solving LLG equation.…”

Section: Néel-type Magnetic Kinksmentioning

confidence: 99%

“…[2-6, 8, 9]. These fascinating physical properties also inspired an ongoing search for new types of magnetic topological textures, for instance, fractional skyrmion emerging in various chiral and frustrated magnets [15][16][17][18][19][20][21], which exhibit some unusual physical phenomena distinctly different from skyrmion-host chiral magnetic materials such as MnSi and Fe 1-x Co x Si systems [22,23]. Moreover, some recent observations indicated that fractional skyrmions also emerge in geometric nanostructures due to the effects of geometric confinement and shape anisotropy [24][25][26][27][28].…”

Section: Introductionmentioning

confidence: 99%

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Control of Néel-type Magnetic Kinks Confined in a Square Nanostructure by Spin-Polarized Currents

et al. 2021

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Magnetic skyrmion in chiral magnet exhibits a variety of unique topological properties associated with its innate topological structure. This inspires a number of ongoing searching for new topological magnetic textures. In this work, we used micromagnetic simulations and Monte Carlo simulations to investigate an exotic Néel-type magnetic kinks in square-shaped nanostructures of chiral magnets, which performs rather stably in the absence of magnetic field. The individual magnetic kink can reside in one of the four possible corners, and carry possibly upward or downward core polarity, constituting eight degenerate states. In addition, these kinks also exhibit unique behaviors of generation, stability and dynamics, as revealed by micromagnetic simulations. It was found that such kinks can be created, annihilated, displaced, and polarity-reversed on demand by applying a spin-polarized current pulse, and are easily switchable among the eight degenerate states. In particularly, the kinks can be switched toward the ferromagnetic-like states and backward reversibly by applying two successive current pulses, indicating the capability of writing and deleting the kink structures. These findings predict the existence of Néel-type magnetic kinks in the square-shaped nanostructures, as well as provide us a promising approach to tailor the kinks by utilizing the corners of the nanostructures, and control these states by spin-polarized currents. The present work also suggests a theoretical guide to explore other chiral magnetic textures in nanostructures of polygon geometries.

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Section: Model and Simulation Methodsmentioning

confidence: 99%

Section: Néel-type Magnetic Kinksmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Control of Néel-type Magnetic Kinks Confined in a Square Nanostructure by Spin-Polarized Currents

et al. 2021

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“…It is well known that the skyrmion structure usually arises as a result of energy competition among the exchange energy, Dzyaloshinskii-Moriya interaction (DMI), demagnetization energy, magnetic anisotropy and Zeeman energy [8]. Previous studies demonstrated that various types of anisotropy terms (e.g., perpendicular magnetic anisotropy (PMA), easy-plane magnetocrystalline anisotropy and cubic anisotropy) may play a prominent role in modulating the skyrmion structures and enhancing their stability [17][18][19][20][21][22][23][24][25]. For instance, PMA can help create and stabilize skyrmions, regulate their structures [13,17,18,26,27], and even enables the stabilization of skyrmion at zero magnetic field in confined nanostructures [8].…”

Section: Of 14mentioning

confidence: 99%

Manipulation of Skyrmion Motion Dynamics for Logical Device Application Mediated by Inhomogeneous Magnetic Anisotropy

et al. 2022

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Magnetic skyrmions are promising potential information carriers for future spintronic devices owing to their nanoscale size, non-volatility and high mobility. In this work, we demonstrate the controlled manipulation of skyrmion motion and its implementation in a new concept of racetrack logical device by introducing an inhomogeneous perpendicular magnetic anisotropy (PMA) via micromagnetic simulation. Here, the inhomogeneous PMA can be introduced by a capping nano-island that serves as a tunable potential barriers/well which can effectively modulate the size and shape of isolated skyrmion. Using the inhomogeneous PMA in skyrmion-based racetrack enables the manipulation of skyrmion motion behaviors, for instance, blocking, trapping or allowing passing the injected skyrmion. In addition, the skyrmion trapping operation can be further exploited in developing special designed racetrack devices with logic AND and NOT, wherein a set of logic AND operations can be realized via skyrmion–skyrmion repulsion between two skyrmions. These results indicate an effective method for tailoring the skyrmion structures and motion behaviors by using inhomogeneous PMA, which further provide a new pathway to all-electric skyrmion-based memory and logic devices.

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“…They include calculations based on a classical spin model, an itinerant electron model, and an effective Ginzburg-Landau functional. These theories enable us to grasp a physical insight into the skyrmion lattice formation and, indeed, the importance of the magnetic frustrations [39,40], compass anisotropy of the magnetic interactions [41,42], higher-order spin interactions [43,44], and Fermi surface nesting [45,46] have been recognized as an essential property to stabilize the skyrmion lattice phase (for more details, see Ref. [47]).…”

Section: Introductionmentioning

confidence: 99%

Ab initio exploration of short-pitch skyrmion materials: Role of orbital frustration

Nomoto

Arita

2023

Journal of Applied Physics

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In recent years, the skyrmion lattice phase with a short lattice constant has attracted attention due to its high skyrmion density, making it a promising option for achieving high-density storage memory and for observing novel phenomena like the quantized topological Hall effect. Unlike conventional non-centrosymmetric systems where the Dzyaloshinsky–Moriya interaction plays a crucial role, the short pitch skyrmion phase requires a quadratic magnetic interaction [Formula: see text] with a peak at finite-[Formula: see text], and weak easy-axis magnetic anisotropy is also critical. Thus, conducting first-principles evaluations is essential for understanding the formation mechanism as well as for promoting the discovery of new skyrmion materials. In this Perspective, we focus on recent developments of the first-principles evaluations of these properties and apply them to the prototype systems Gd[Formula: see text] and Eu[Formula: see text], where [Formula: see text] denotes a transition metal and [Formula: see text] represents Si or Ge. In particular, based on the spin density functional theory with the Hubbard correction combined with the Liechtenstein method in the Wannier tight-binding model formalism, we first show that the Hubbard [Formula: see text] and Hund’s coupling is essential to stabilize a skyrmion lattice state by enhancing the easy-axis anisotropy. We then discuss mechanisms of finite-[Formula: see text] instability and show that competition among Gd-5[Formula: see text] orbitals determines whether ferromagnetism or a finite-[Formula: see text] structure is favored in Gd[Formula: see text]Si[Formula: see text] with [Formula: see text] Fe and Ru. Our systematic calculations reveal that GdRu[Formula: see text], GdOs[Formula: see text], and GdRe[Formula: see text] are promising, while GdAg[Formula: see text], GdAu[Formula: see text], and EuAg[Formula: see text] are possible candidates as the skyrmion host materials. Analysis based on a spin spiral calculation for the candidate materials is also presented.

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Compass-anisotropy-modulated helical states and skyrmion crystals in chiral magnets

Cited by 3 publications

References 26 publications

Control of Néel-type Magnetic Kinks Confined in a Square Nanostructure by Spin-Polarized Currents

Control of Néel-type Magnetic Kinks Confined in a Square Nanostructure by Spin-Polarized Currents

Manipulation of Skyrmion Motion Dynamics for Logical Device Application Mediated by Inhomogeneous Magnetic Anisotropy

Ab initio exploration of short-pitch skyrmion materials: Role of orbital frustration

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