Large exchange-dominated domain wall velocities in antiferromagnetically coupled nanowires

Kuteifan, M.; Lubarda, Marko V.; Fu, Sidi; Chang, Ramsay; Escobar, Marco Antonio Camacho; Mangin, Stéphane; Fullerton, Eric E.; Lomakin, Vitaliy

doi:10.1063/1.4945789

Cited by 11 publications

(8 citation statements)

References 19 publications

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“…9,26 Similarly, significantly enhanced DW velocities and a deferred Walker breakdown have been reported for current induced DW motion in synthetic AFMs, where the antiferromagnetic coupling between the two ferromagnetic layers stabilizes the domain wall structure. 27,28 The progress in controlling magnetic states in AFMs is due to the fact that staggered spin transfer torques can be observed in AFMs with broken inversion symmetry. Systems with artificially or intrinsically broken inversion symmetry have recently attracted much of interest because of their connection to topology.…”

Section: Introductionmentioning

confidence: 99%

Domain walls in antiferromagnets: The effect of Dzyaloshinskii–Moriya interactions

Conzelmann

Selzer

Nowak

2020

Journal of Applied Physics

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Section: Introductionmentioning

confidence: 99%

Domain walls in antiferromagnets: The effect of Dzyaloshinskii–Moriya interactions

Conzelmann

Selzer

Nowak

2020

Journal of Applied Physics

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“…This is very important for experiments and technical applications using pulsed driving forces, since one could operate on much shorter time scales. Furthermore, the argument of counteracting torques leading to massless DWs is not restricted to temperature gradients but also applies to other driving mechanisms in antiferromagnets featuring staggered torques, like Néel spin-orbit torques [29] or current driven DW motion in synthetic antiferromagnets [8,31].…”

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confidence: 99%

Inertia-Free Thermally Driven Domain-Wall Motion in Antiferromagnets

et al. 2016

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Domain wall motion in antiferromagnets triggered by thermally induced magnonic spin currents is studied theoretically. It is shown by numerical calculations based on a classical spin model that the wall moves towards the hotter regions, as in ferromagnets. However, for larger driving forces the so called Walker breakdown which usually speeds down the wall is missing. This is due to the fact that the wall is not tilted during its motion. For the same reason antiferromagnetic walls have no inertia and, hence, no acceleration phase leading to higher effective mobility.The interest in antiferromagnetic and ferrimagnetic materials has increased recently for several reasons. One is the more complex spin structures which lead to additional spin wave modes with higher frequencies and, consequently, faster spin dynamics than in ferromagnets (FMs). Possible applications are in the field of ultrafast spin dynamics [1,2]. Also, ferrimagnets and antiferromagnets (AFMs) have attracted a lot of attention as low-damping, insulating magnets in the emerging field of spincaloritronics [3][4][5] which is on the combined transport of spin and heat. Finally, antiferromagnets are also discussed as future material for antiferromagnetic spintronics, since it has been shown that despite their lack of a macroscopic magnetization their magnetic state can be controlled via spin torque switching and can be read out via their magnetoresistive properties [6]. Spintronic phenomena call for exploitation in devices with magnetic storage functionalities, where a magnetic nanostructure has to be controlled efficiently and fast. The information can be stored in magnetic domains, in isolated magnetic nanoparticles, or even in domain walls (DWs) [7]. For the latter case synthetic AFMs have been shown to pave a new road towards higher DW mobility [8].For a ferromagnetic system, in Ref.[9] the existence of thermally driven domain-wall motion in temperature gradients was demonstrated by computer simulations based on different approaches, an atomistic spin model as well as a micromagnetic model based on the Landau-Lifshitz-Bloch (LLB) equation of motion. A thermodynamic explanation for this kind of DW motion rests on the minimization of the free energy of the DW (or the maximization of entropy). For a DW at finite temperature, the free energy is ΔFðTÞ ¼ ΔU − TΔS, where ΔU is the internal energy and ΔS the entropy of the DW. It is a monotonically decreasing function of temperature [9][10][11]. This rather general argument explains a DW motion towards the hotter parts of the sample where the free energy is lower [11][12][13] and it can be expected to hold for other magnetic textures as well. Furthermore, it has been shown by Schlickeiser et al.that the DW motion is caused by a so-called entropic torque. The exchange stiffness is weaker for higher temperature and therefore, an effective torque on the DW is created driving it towards the hotter region [11].A more microscopic explanation for DW motion in temperature gradients rests on the continuous stream of ...

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“…5 Quite recently, it has been proposed that synthetic antiferromagnets and ferrimagnets with perpendicular-to-plane magnetized layers can provide an interesting solution for the operation of racetrack memories since domain walls in these systems can reach high velocities. 9 In addition, they show an almost vanishing magnetic stray field, which is useful for integrated circuits because the stray field is the primary obstacle for closely packed domain walls. 6,7 With future spintronic applications in mind, micromagnetic simulation or experimental studies in synthetic antiferromagnets have been focussed on domain wall movement through DC currents.…”

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confidence: 99%

“…6,7 With future spintronic applications in mind, micromagnetic simulation or experimental studies in synthetic antiferromagnets have been focussed on domain wall movement through DC currents. [7][8][9] However, the understanding of the domain wall dynamics in these systems under the impact of magnetic fields is crucial to predict the stability and robustness of future devices. This is especially true if the antiferromagnetically exchange coupled layer system is not fully compensated (synthetic ferrimagnet) or if the coupling strength between the layers is not strong enough to exclude a deviation from the antiferromagnetic coupling during the motion.…”

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confidence: 99%

“…For instance, when an antiparallel state (e.g., AP þ ) is nucleated in the inverse antiparallel state (AP -), then for a field pulse amplitude which is small in comparison to the exchange coupling field between the two layers, the domain grows, whereas for large field pulse amplitudes, the direction of the domain displacement is inverted. Thus, synthetic ferrimagnetic systems would be suitable for large domain velocity as predicted 9 if the interlayer exchange coupling is strong enough to prevent a ferromagnetic alignment during the domain wall propagation.…”

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confidence: 99%

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Inversion of the domain wall propagation in synthetic ferrimagnets

Hamadeh

Pirro

Adam

et al. 2017

Applied Physics Letters

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We report on magnetic domain wall velocity measurements in a synthetic ferrimagnet made of two perpendicular ferromagnetic layers antiferromagnetically exchange coupled. In this system, two types of transitions may be observed: one from a parallel alignment to an antiparallel alignment of the magnetization of the two layers and the other between the two possible antiparallel alignments. Those transitions are shown to be dominated by domain wall propagation. The domain wall velocity as a function of the applied magnetic field pulse amplitude has been measured. Two remarkable features are observed: first, a drastic breakdown of the domain wall velocity and then an inversion of the domain propagation direction are observed when the field pulses reach values comparable to the exchange field between the two layers. This unexpected behavior can be understood qualitatively using a simple model taking into account the competition between interlayer exchange coupling and the external driving field.

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Large exchange-dominated domain wall velocities in antiferromagnetically coupled nanowires

Cited by 11 publications

References 19 publications

Domain walls in antiferromagnets: The effect of Dzyaloshinskii–Moriya interactions

Domain walls in antiferromagnets: The effect of Dzyaloshinskii–Moriya interactions

Inertia-Free Thermally Driven Domain-Wall Motion in Antiferromagnets

Inversion of the domain wall propagation in synthetic ferrimagnets

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