Effects of anisotropic exchange on the micromagnetic domain structures

Schaadt, D. M.; Engel‐Herbert, Roman; Hesjedal, T.

doi:10.1002/pssb.200642613

Cited by 7 publications

(5 citation statements)

References 19 publications

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“…The saturation magnetization and anisotropy constant were set to the values obtained from the VSM measurements. To fit micromagnetic simulations results with the BLS data, we had to assume an anisotropic exchange constant, [54][55][56] with Aex,IP=1.45×10 -6 erg/cm and Aex,OOP=1.05×10 -6 erg/cm along the IP and OOP directions, respectively. Micromagnetic simulations were performed for the system of thickness Lz=42.5 nm discretized with the unit cell of dimensions being much smaller than the exchange length or the width of domain walls.…”

Section: Micromagnetic Simulationsmentioning

confidence: 99%

Magnonic band structure in a Co/Pd stripe domain system investigated by Brillouin light scattering and micromagnetic simulations

et al. 2017

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By combining Brillouin Light Scattering and micromagnetic simulations we studied the spin-wave dynamics of a Co/Pd thin film multilayer, features a stripe domain structure at remanence. The periodic up and down domains are separated by cork-screw type domain walls. The existence of these domains causes a scattering of the otherwise bulk and surface spin-wave modes, which form mode families, similar to a one dimensional magnonic crystal. The dispersion relation and mode profiles of spin waves are measured for transferred wave vector parallel and perpendicular to the domain axis.The possibility to use spin-waves (SW) to excite, transmit, store, and retrieve electric signals as well as to perform logical operations has fueled a new spectrum of research in the wavebased signal processing technology [1-4]. Usually, magnonic crystals (MC), i.e. arrays of macroscopic magnetic stripes [5], dots [6], antidots [7], etched grooves or pits[1], periodic variations of the internal magnetic field [9] and saturation magnetization by ion implantation [10], are employed to control the flow of SWs. Magnetostatic surface SWs or the Damon-Eshbach (DE) SW modes, which propagate perpendicular to the in-plane (IP) magnetization direction, are promising in this context because of their large group velocities (vg) and low attenuation.Consequently, significant progress has been made towards the practical realization of magnonic devices in terms of the on-chip generation, directional channeling, detection and manipulation of SWs. However, to realize the experimental geometry, a large magnetic field has to be applied to enforce the magnetization perpendicular to the SW propagation direction. This is a major obstacle to the implementation of a MC into a practical device. A way out is to use the Oersted field generated from an underlying current-carrying stripe [11][12], which is still plagued by the problem of generation of waste heat which increases with increasing data processing speed. Moreover, the fabrication of periodic nanostructures involves high-precision electron-beam lithography which is very complex and expensive. An alternative approach to overcome these fundamental drawbacks is to take recourse to the spin dynamics in the remanent state, which is more suitable for nanoscale device applications, as it does not require any stand-by power once initialized.In the literature, only few reports exist on the magnetization dynamics for systems with an inhomogeneous magnetization distribution containing domains and domain walls. Most commonly studied is a periodic or non-periodic distribution of magnetic units of up and down domains (parallel, labyrinthine, bubble-like domains) [13][14][15][16][17][18][19], separated by negligibly thin, onedimensional domain walls. Such domains appear in magnetic thin films with a perpendicular anisotropy smaller than the demagnetizing energy if the film thickness is higher than a critical value tc, which is, in turn, dependent on the perpendicular anisotropy constant, saturation magnetization and the exc...

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Section: Micromagnetic Simulationsmentioning

confidence: 99%

Magnonic band structure in a Co/Pd stripe domain system investigated by Brillouin light scattering and micromagnetic simulations

et al. 2017

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“…However, hexagonal symmetry also allows for inter-site anisotropy terms of the form -J z (M i z M j z ). Such anisotropic exchange has been examined in the cases Co and Fe ions [2,3] and has previously been included in a micromagnetic calculation of domain structures in MnAs films [4].…”

Section: Introductionmentioning

confidence: 99%

“…M j z ). Such anisotropic exchange has been examined in the cases Co and Fe ions [2,3] and has previously been included in a micromagnetic calculation of domain structures in MnAs films [4].…”

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confidence: 99%

Impact of Anisotropic Exchange on M-H Loops: Application to ECC Media

2009

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Micromagnetic simulation results on Co-based recording media are presented which examine the impact of a modified near-neighbor exchange interaction between grains of the form Jz(MizMjz), reflecting the hexagonal crystal symmetry. Both out-of-plane and in-plane M-H loops are calculated, with an emphasis on a model fit to data reported by Wang et al. [IEEE Trans. Magn. vol. 43, 682 (2007)] on exchange coupled composite perpendicular media. The principle effect of Jz is to increase the coercivity and slope of both hard and soft layers. Improved agreement with experimental data for the in-plane loops is achieved by assuming a substantial value for Jz. Possibilities for measurement of Jz through spin-wave excitations are discussed. Thermal fluctuation effects are also examined through simulations of the magnetization vs temperature.Comment: 4 pages, 9 figure

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“…For a few systems, however, the orientation and anisotropy of the crystal lattice matter. To explain the shape and orientation of the domains, in some of these cases the anisotropy of the spin stiffness must be taken into account, 6,7 while in others only certain spatial orientations of the domain walls minimize the sum of the magnetostatic stray-field energy and the magnetocrystalline anisotropy energy. 8 In this Rapid Communication we report on a different mechanism on how the domain-wall orientation is linked to the crystal lattice.…”

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Dzyaloshinskii-Moriya interaction accounting for the orientation of magnetic domains in ultrathin films: Fe/W(110)

2008

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Combining relativistic first-principles calculations with a micromagnetic model, we establish the Dzyaloshinskii-Moriya interaction as an important mechanism in thin-film magnetism, determining the orientation of magnetic domains relative to the lattice, the type of domain wall, and the rotational direction of the magnetization in the wall. Applying the analysis to two monolayers Fe on W͑110͒, we provide an explanation for puzzling experimental data obtained by spin-polarized scanning tunneling microscopy. DOI: 10.1103/PhysRevB.78.140403 PACS number͑s͒: 75.70.Ak, 71.15.Mb, 75.60.Ch Understanding the nature of domains and domain walls in magnetic nanostructures has become an important issue in the field of spintronics as the controlled motion of domain walls opens up vistas for new types of memory and logic devices ͑e.g., Refs. 1 and 2͒. Domain walls in nanostructures and thin films are known to originate from the interplay of the quantum-mechanical exchange interaction ͑also expressed as spin stiffness͒, the magnetocrystalline anisotropy caused by the relativistic spin-orbit coupling ͑SOC͒, and the classical long-ranged magnetostatic contribution. Usually, the shape of the domains is at random or depends on the size and geometry of the sample. [3][4][5] In these instances there is no correlation between the relative orientation of the domains and the crystal lattice. For a few systems, however, the orientation and anisotropy of the crystal lattice matter. To explain the shape and orientation of the domains, in some of these cases the anisotropy of the spin stiffness must be taken into account, 6,7 while in others only certain spatial orientations of the domain walls minimize the sum of the magnetostatic stray-field energy and the magnetocrystalline anisotropy energy. 8 In this Rapid Communication we report on a different mechanism on how the domain-wall orientation is linked to the crystal lattice. For an ultrathin Fe film, we found out that the Dzyaloshinskii-Moriya interaction ͑DMI͒ plays the crucial role accounting for the orientation of the walls and further for the type of the wall and the rotational direction of the magnetization in the wall. The DMI is an antisymmetric exchange interaction that favors spatially rotating magnetic structures of a specific rotational direction.9,10 It vanishes in inversion-symmetric crystal structures; therefore, it can be excluded for most simple bulk materials. In surface or interface geometries, however, the inversion symmetry is broken and the DMI may become relevant.11 In a recent work 12 it was demonstrated for the first time that on some surfaces the DMI is so strong that it even dominates over the symmetric exchange interactions and induces a spatially rotating magnetic ground state.In this study, we describe the domain walls by a micromagnetic model in which the DMI is included. In contrast to earlier work, we determine all model parameters quantitatively from their electronic origin by first-principles calculations and thus we are able to draw conclusions on th...

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Effects of anisotropic exchange on the micromagnetic domain structures

Cited by 7 publications

References 19 publications

Magnonic band structure in a Co/Pd stripe domain system investigated by Brillouin light scattering and micromagnetic simulations

Magnonic band structure in a Co/Pd stripe domain system investigated by Brillouin light scattering and micromagnetic simulations

Impact of Anisotropic Exchange on M-H Loops: Application to ECC Media

Dzyaloshinskii-Moriya interaction accounting for the orientation of magnetic domains in ultrathin films: Fe/W(110)

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