Spin wave emission in field-driven domain wall motion

Field-driven domain wall (DW) motion in ferromagnetic nanowires with easy- and hard-axis anisotropies was studied theoretically and numerically in the presence of the bulk Dzyaloshinskii-Moriya interaction (DMI) based on the Landau-Lifshitz-Gilbert equation. We propose a new trial function and offer an exact solution for DW motion along a uniaxial nanowire driven by an external magnetic field. A new strategy was suggested to speed up DW motion in a uniaxial magnetic nanowire with large DMI parameters. In the presence of hard-axis anisotropy, we find that the breakdown field and velocity of DW motion was strongly affected by the strength and sign of the DMI parameter under external fields. This work may be useful for future magnetic information storage devices based on DW motion.

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“…We now considered a classical Heisenberg biaxial chain along z direction with the DMI in an external field H 43 44 …”

Section: Numerical Results and Discussionmentioning

confidence: 99%

Field-driven Domain Wall Motion in Ferromagnetic Nanowires with Bulk Dzyaloshinskii-Moriya Interaction

Zhuo

Sun

2016

Sci Rep

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“…This process transfers energy from the DW to the domains where it is quickly dissipated. Such mechanism, neglected by the 1D model of Walker and Slonczewski, has been investigated numerically in one-dimensional systems where it has been shown that spin waves emission from the DW can take place and contribute to DW motion when a strong hard-axis anisotropy is present in the system [29][30][31] and also in in-plane magnetized permalloy strips in presence of various forms of disorder [16,32]. In our system, both disorder and the fact that the wall is extended in length play a role, as discussed below.…”

Section: Energy Dissipationmentioning

confidence: 99%

Disorder-induced domain wall velocity shift at high fields in perpendicularly magnetized thin films

et al. 2016

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Domain wall dynamics in a perpendicularly magnetized system is studied by means of micromagnetic simulations in which disorder is introduced as a dispersion of both the easy-axis orientation and the anisotropy constant over regions reproducing a granular structure of the material. High field dynamics show a linear velocity-field relationship and an additional grain size dependent velocity shift, weakly dependent on both applied field and intrinsic Gilbert's damping parameter. We find the origin of this velocity shift in the nonhomogeneous in-plane effective field generated by the tilting of anisotropy easy axis introduced by disorder. We show that a one-dimensional analytical approach cannot predict the observed velocities and we augment it with the additional dissipation of energy arising from internal domain wall dynamics triggered by disorder. This way we prove that the main cause of higher velocity is the ability of the domain wall to irradiate energy into the domains, acquired with a precise feature of disorder.

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“…The Walker breakdown is related to the instability of domain walls, for example, spin waves may be emitted when a transverse DW travels in a thin strip [13,14]. Micromagnetic simulations show that a moving DW in cylindrical nanowires has an almost vanishing mass [3,15].…”

Section: Introductionmentioning

confidence: 99%

“…b) shows a contour plot of the dissipation rate ω i as a function of β and q for α = 0.02 and b = −0.15, it is found that in the top right corner ω i is negative, which indicates that β term may leads to a negative dissipation rate if |b| < 2. For the case that α = 0 and b = 0, the solution of ψ(ξ, τ ) reduces to ψ(ξ, τ ) = ψ 2 0 /2 a + iτ e i[q0ξ−(1+q 2 0 )τ ]−(ξ−2q0τ ) 2 /4(a+iτ )(14) …”

mentioning

confidence: 99%

Current-induced instability of domain walls in cylindrical nanowires

Wang¹,

Zhang²,

Pepper³

et al. 2017

J. Phys.: Condens. Matter

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We study the current-driven domain wall (DW) motion in cylindrical nanowires using micromagnetic simulations by implementing the Landau-Lifshitz-Gilbert equation with nonlocal spin-transfer torque in a finite difference micromagnetic package. We find that in the presence of DW, Gaussian wave packets (spin waves) will be generated when the charge current is suddenly applied to the system. This effect is excluded when using the local spin-transfer torque. The existence of spin waves emission indicates that transverse domain walls can not move arbitrarily fast in cylindrical nanowires although they are free from the Walker limit. We establish an upper velocity limit for DW motion by analyzing the stability of Gaussian wave packets using the local spin-transfer torque. Micromagnetic simulations show that the stable region obtained by using nonlocal spin-transfer torque is smaller than that by using its local counterpart. This limitation is essential for multiple DWs since the instability of Gaussian wave packets will break the structure of multiple DWs.

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Spin wave emission in field-driven domain wall motion

Cited by 21 publications

References 28 publications

Field-driven Domain Wall Motion in Ferromagnetic Nanowires with Bulk Dzyaloshinskii-Moriya Interaction

Field-driven Domain Wall Motion in Ferromagnetic Nanowires with Bulk Dzyaloshinskii-Moriya Interaction

Disorder-induced domain wall velocity shift at high fields in perpendicularly magnetized thin films

Current-induced instability of domain walls in cylindrical nanowires

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