Magnetization splitting in Landau and diamond-domain structures: Dependence on exchange interaction, anisotropy, and size

Xie, Kaixuan; Zhang, Xiaopu; Lin, Weiwei; Zhang, Peng; Sang, H.

doi:10.1103/physrevb.84.054460

Cited by 8 publications

(4 citation statements)

References 26 publications

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“…The cross-tie state is well described in the literature. 23 The vortex diamond state coincides with the described antivortex one up to interchanging of positions of vortices and antivortices, this state was already observed in rectangular [24][25][26] and elliptical 27 nanopaticles and also in mesoscopic islands of complicated form. 24 The quasicrystal state is very similar to the vortex-antivortex lattice recently predicted for wide films 10,11 .…”

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confidence: 60%

Periodic magnetic structures generated by spin–polarized currents in nanostripes

Volkov¹,

Kravchuk²,

Sheka³

et al. 2013

Appl. Phys. Lett.

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The influence of a spin-polarized current on long ferromagnetic nanostripes is studied numerically. The current flows perpendicularly to the stripe. The study is based on the Landau-Lifshitz phenomenological equation with the Slonczewski-Berger spin-torque term. The magnetization behavior is analyzed for all range of the applied currents, up to the saturation. It is shown that the saturation current is a nonmonotonic function of the stripe width. For a stripe width increasing it approaches the saturation value for an infinite film. A number of stable periodic magnetization structures are observed below the saturation. Type of the periodical structure depends on the stripe width. Besides the one-dimensional domain structure, typical for narrow wires, and the two-dimensional vortex-antivortex lattice, typical for wide films, a number of intermediate structures are observed, e.g. cross-tie and diamond state. For narrow stripes an analytical analysis is provided.PACS numbers: 75.10. Hk, 75.40.Mg, 72.25.Ba, A magnetic nanostripe is a convenient system for studying the dynamics of magnetization structures driven by a spin-polarized current. Typically the current is passed along the stripe, which causes a movement of the domain wall. This phenomenon is widely studied both theoretically and experimentally, see e.g. reviews 1-4. Nevertheless the influence of a perpendicular current on the stripe magnetization dynamics is also of high interest for spintronic applications. Recently it was predicted theoretically 5 and later confirmed experimentally 6-9 that the perpendicular current can excite the domain wall motion with much higher velocity comparing to the in-plane current.Recently we have studied the action of the strong perpendicular spin-polarized current on a nanomagnet for two limit cases, namely a planar two-dimensional film 10,11 and a narrow one-dimensional wire 12 . In both cases a stable periodical structure induced by the spincurrent is found in the pre-saturated regime: a square vortex-antivortex lattice is formed in a film and a onedimensional domain structure is formed in a wire. The aim of this paper is to make a link between these limit cases. For this purpose we consider thin and long stripe shaped samples of different widths. By varying the stripe width we study the current induced magnetization behavior in wide range, starting from quasi-one dimensional narrow strips (w/h 1) and up to quasi two-dimensional wide strips (w/h 1), where w and h denote respectively the stripe width and thickness. The following analysis is made under the assumption that the stripe is sufficiently long, so that L w and L h with L being the stripe length. We also assume that the stripe is thin enough to ensure uniformity of the magnetization along the thickness. Details of the problem geometry are shown in Fig. 1.Our study is based on the Landau-Lifshitz-Slonczewski phenomenological equation [13][14][15] : where m = M /M s = (m x , m y , m z ) is the normalized magnetization, M s is the saturation magnetization. The overdot in...

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supporting

confidence: 60%

Periodic magnetic structures generated by spin–polarized currents in nanostripes

Volkov¹,

Kravchuk²,

Sheka³

et al. 2013

Appl. Phys. Lett.

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“…In this paper, we considered four starting configurations of which only two resulted into physically acceptable equilibrium magnetization states. Other starting conditions could also be taken into account, see, for example, . All the obtained equilibrium configurations are (meta)stable states which can exist next to each other.…”

Section: Discussionmentioning

confidence: 99%

A 2.5D micromagnetic modeling approach for magnetic domain and domain wall studies

Wiele

Vansteenkiste

Waeyenberge

et al. 2013

Int J Numerical Modelling

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There is a long standing interest in the structure of domains and domain walls in various magnetic material samples. Here, the micromagnetic theory is able to describe how material parameters, excitation conditions and sample geometry influences the magnetization state and its temporal evolution. In the theory, the Landau-Lifshitz (LL) equation describes how the magnetization evolves on a picosecond time scale and a nanometer space scale. Due to its highly non-linear character, one can in most cases only rely on numerical computational schemes to solve the LL-equation. If one aims at structurally investigating domain and domain wall structures in a comprehensive way, large parameter scans need to be undertaken on possibly large samples, which is computationally intensive.For some geometries, a first possibility to reduce the computational burden is to apply a 2.5D approach. Here, the sample is considered infinite in one direction. Along this direction all material and field quantities are assumed invariant, but still retain their 3D vector character. This makes a 2D discretization of the geometry possible and reduces the computational burden for the evaluation of the magnetic fields, compared to a full 3D description. This approach is particularly valuable as an alternative to the analytics based domain theory which often starts from the same assumptions (A. Hubert and R. Schäfer, Magnetic domains, Springer Verlag, Berlin, Heidelberg, New York, 1998).A second way to accelerate the numerical simulations is to implement the algorithms on Graphical Processing Units (GPUs). In the last years the huge parallel computational power available in this hardware, originally developed for highspeed image rendering, has drastically reduced computation times in various numerical research domains. In this contribution, we present the 2.5D micromagnetic approach and comment on its GPU-specific implementation.

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“…To understand the origin of the different switching fields observed in figure 4, we have performed micromagnetic simulations that provide detailed information about the dependence of magnetic behavior on material parameters and geometry [18]. Although there are many calculations done for micrometer sized rectangular structures [19,20], one can expect that further reduction of the size to the nanometer scale, together with an increase of the aspect ratio, can lead to a different and/ or more complex energy landscape.…”

Section: Micromagnetic Simulations Of a 2d Array Of Nanomagnetsmentioning

confidence: 99%

Tailoring the magnetization states in 2D arrays of multiresponse ferromagnetic nanomagnets

Abuín

Maícas

García

et al. 2017

J. Phys. D: Appl. Phys.

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We have fabricated Fe 52−54 Co 46−48 nanomagnet arrays as a function of several geometrical parameters like the spacing between nanostructures, the aspect ratio and the layers thicknesses. The nanomagnets consist in two magnetic layers, separated by a non magnetic interlayer, that interact through magnetostatic coupling. They present a multiresponse hysteresis loops with two dierent switching elds. We have performed micromagnetic simulations to discern the role play by the dierent interactions. The spacing in the array strongly modies the saturating eld along the short axis and the magnetization reversal mechanisms from coherent rotation to domain wall nucleation. A small asymmetry between the two magnetic layers favors a magnetization reversal mechanism along the long axis with two dierent switching elds. These elds can be tailored through the thickness of the layers or the inter-element spacing in the array. In trilayers with the same magnetic layer thicknesses, the asymmetry can be induced by growing the two magnetic layers with a dierent anisotropy. The well-dened reversal elds make these nanomagnets potentially useful for magnetic tagging.

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Magnetization splitting in Landau and diamond-domain structures: Dependence on exchange interaction, anisotropy, and size

Cited by 8 publications

References 26 publications

Periodic magnetic structures generated by spin–polarized currents in nanostripes

Periodic magnetic structures generated by spin–polarized currents in nanostripes

A 2.5D micromagnetic modeling approach for magnetic domain and domain wall studies

Tailoring the magnetization states in 2D arrays of multiresponse ferromagnetic nanomagnets

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