Topological dynamics and current-induced motion in a skyrmion lattice

Martı́nez, J. C.; Jalil, M. B. A.

doi:10.1088/1367-2630/18/3/033008

Cited by 25 publications

(11 citation statements)

References 26 publications

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“…In Ref. 28 the study of the Thiele equation was carried for current-induced motion in a skyrmion lattice through two soluble models of the pinning potential.…”

Section: Introductionmentioning

confidence: 99%

Dzyaloshinskii-Moriya interaction in magnetoferroelectric superlattices: Spin waves and skyrmions

2019

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We study in this paper effects of Dzyaloshinskii-Moriya (DM) magnetoelectric coupling between ferroelectric and magnetic layers in a superlattice formed by alternate magnetic and ferroelectric films. Magnetic films are films of simple cubic lattice with Heisenberg spins interacting with each other via an exchange J and a DM interaction with the ferroelectric interface. Electrical polarizations of ±1 are assigned at simple cubic lattice sites in the ferroelectric films. We determine the ground-state (GS) spin configuration in the magnetic film. In zero field, the GS is periodically non collinear and in an applied field H perpendicular to the layers, it shows the existence of skyrmions at the interface. Using the Green's function method we study the spin waves (SW) excited in a monolayer and also in a bilayer sandwiched between ferroelectric films, in zero field. We show that the DM interaction strongly affects the long-wave length SW mode. We calculate also the magnetization at low temperature T . We use next Monte Carlo simulations to calculate various physical quantities at finite temperatures such as the critical temperature, the layer magnetization and the layer polarization, as functions of the magnetoelectric DM coupling and the applied magnetic field. Phase transition to the disordered phase is studied in detail.

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“…In Ref. 28 the study of the Thiele equation was carried for current-induced motion in a skyrmion lattice through two soluble models of the pinning potential.…”

Section: Introductionmentioning

confidence: 99%

Dzyaloshinskii-Moriya interaction in magnetoferroelectric superlattices: Spin waves and skyrmions

2019

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“…The Magnus force can strongly affect how the skyrmions move under an external drive and in the presence of disorder or a confining potential. It can produce a drive-dependent skyrmion Hall angle due to velocity-dependent asymmetric scattering of the skyrmions by defects [58,59,60,61,62,63], spiraling skyrmion motion around defects [58,64,65,66,67,68,69], and speed up effects [58,70,69,71,72] where the pinning force in combination with the Magnus effect can accelerate the skyrmion. Since skyrmions also show promise for various applications [73,74,75], understanding how to control skyrmion motion in the presence of nanostructured pinning arrays could be a promising approach for creating skyrmion based devices.…”

Section: Introductionmentioning

confidence: 99%

Skyrmion Dynamics and Transverse Mobility: Skyrmion Hall Angle Reversal on 2D Periodic Substrates with dc and Biharmonic ac Drives

Vizarim,

Reichhardt,

Venegas

et al. 2020

Preprint

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We numerically examine the dynamics of a skyrmion interacting with a two-dimensional periodic substrate under dc and biharmonic ac drives. We show that the Magnus force of the skyrmion produces circular orbits that can resonate with the ac drive and the periodicity of the substrate to create quantized motion both parallel and perpendicular to the dc drive. The skyrmion Hall angle exhibits a series of increasing and/or decreasing steps along with strongly fluctuating regimes. In the phase locked regimes, the skyrmion Hall angle is constant and the skyrmion motion consists of periodic orbits encircling an integer number of obstacles per every or every other ac drive cycle. We also observe phases in which the skyrmion moves at 90 • with respect to the driving direction even in the presence of damping, a phenomenon called absolute transverse mobility that can exhibit reentrance as a function of dc drive. When the biharmonic ac drives have different amplitudes, in the two directions we find regimes in which the skyrmion Hall angle shows a sign reversal from positive to negative, as well as a reentrant pinning effect in which the skyrmion is mobile at low drives but becomes pinned at higher drives. These behaviors arise due to the combination of the Magnus force with the periodic motion of the skyrmions, which produce Shapiro steps, directional locking, and ratchet effects.

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“…One of the most prominent effects of the Magnus force is that the skyrmions move at an angle with respect to the applied driving force which is known as the skyrmion Hall angle θ sk 27 , as has been observed in simulations [35][36][37][38] and experiments 39,40 . The Magnus force strongly modifies the interaction of the skyrmion with a substrate by creating spiraling motions of skyrmions that are in a trapping potential [40][41][42][43][44][45][46] . The pinning or defects produce a strong drive dependence of the skyrmion Hall angle, which starts off near zero just at depinning and increases with increasing skyrmion velocity before saturating to the intrinsic value at high drives.…”

Section: Introductionmentioning

confidence: 99%

Shapiro Steps and Nonlinear Skyrmion Hall Angles For dc and ac Driven Skyrmions on a Two Dimensional Periodic Substrate

Vizarim,

Reichhardt,

Venegas

et al. 2020

Preprint

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For an overdamped particle moving over a two-dimensional periodic substrate under combined dc and ac drives, a series of steps can appear in the velocity force curves that are known as Shapiro steps. Here we show that for skyrmions driven over a two-dimensional periodic obstacle array with a dc drive and an ac drive that is either parallel or perpendicular to the dc drive, the system exhibits numerous transverse and longitudinal synchronization dynamics due to the Magnus force. These phenomena originate in interactions between two different types of phase locking effects: Shapiro steps and directional locking. In some cases, the skyrmion Hall angle is constant but longitudinal Shapiro steps appear, while in other regimes the skyrmion Hall angle can either increase or decrease with increasing dc drive during the phase locking as the skyrmion locks to different symmetry directions of the obstacle lattice. For a transverse ac drive we find that strong Hall angle overshoots can occur in certain locked phases where the skyrmion is moving at an angle that is considerably larger than the intrinsic Hall angle. For the strongest Magnus force, the phase locking effects are reduced and there are larger regions of disordered dynamics. We show that the skyrmion Hall angle can be controlled by fixing the dc drive and changing the amplitude of the ac drive.

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Topological dynamics and current-induced motion in a skyrmion lattice

Cited by 25 publications

References 26 publications

Dzyaloshinskii-Moriya interaction in magnetoferroelectric superlattices: Spin waves and skyrmions

Dzyaloshinskii-Moriya interaction in magnetoferroelectric superlattices: Spin waves and skyrmions

Skyrmion Dynamics and Transverse Mobility: Skyrmion Hall Angle Reversal on 2D Periodic Substrates with dc and Biharmonic ac Drives

Shapiro Steps and Nonlinear Skyrmion Hall Angles For dc and ac Driven Skyrmions on a Two Dimensional Periodic Substrate

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