scholarly journals Static Properties and Current-Driven Dynamics of Domain Walls in Perpendicular Magnetocrystalline Anisotropy Nanostrips with Rectangular Cross-Section

2012 ◽  
Vol 2012 ◽  
pp. 1-21 ◽  
Author(s):  
Eduardo Martinez
Keyword(s):  
Domain Wall ◽  
Domain Walls ◽  
Magnetocrystalline Anisotropy ◽  
Rectangular Cross Section ◽  
Single Layer ◽  
Domain Wall Motion ◽  
Thermal Fluctuations ◽  
Induced Voltage ◽  
Static Properties ◽  
Voltage Signal

The current-induced domain wall motion along thin ferromagnetic strips with high perpendicular magnetocrystalline anisotropy is studied by means of full micromagnetic simulations and the extended one-dimensional model, taking into account thermal effects and edge roughness. A slow creep regime, where the motion is controlled by wall pinning and thermal activation, and a flow regime with linear variation of the DW velocity, are observed. In asymmetric stacks, where the Rashba spin-orbit field stabilizes the domain wall against turbulent transformations, the steady linear regime is extended to higher currents, leading to higher velocities than in single-layer or symmetric stacks. The pinning and depinning at and from a local constriction were also studied. The results indicate that engineering pinning sites in these strips provide an efficient pathway to achieve both high stability against thermal fluctuations and low-current depinning avoiding Joule heating. Finally, the current-driven dynamics of a pinned domain wall is examined, and both the direct and the alternating contributions to the induced voltage signal induced are characterized. It was confirmed that the direct contribution to the voltage signal can be linearly enhanced with the number of pinned walls, an observation which could be useful to develop domain-wall-based nano-oscillators.

Peierls “Washboard” Controls Dynamics of the Domain Walls in Molecular Ferrimagnets

2015 ◽  
Vol 233-234 ◽  
pp. 55-59
Author(s):  
Marina Kirman ◽  
Artem Talantsev ◽  
Roman Morgunov
Keyword(s):  
Domain Wall ◽  
Crystal Lattice ◽  
Domain Walls ◽  
Low Frequency ◽  
Domain Wall Motion ◽  
Lattice Parameter ◽  
Structural Defects ◽  
Crystal Lattice Parameter ◽  
Wall Width ◽  
Debye Relaxation

The magnetization dynamics of metal-organic crystals has been studied in low frequency AC magnetic field. Four modes of domain wall motion (Debye relaxation, creep, slide and over - barrier motion (switching)) were distinguished in [MnII(H(R/S)-pn)(H2O)] [MnIII(CN)6]⋅2H2O crystals. Debye relaxation and creep of the domain walls are sensitive to Peierls relief configuration controlled by crystal lattice chirality. Structural defects and periodical Peierls potential compete in the damping of the domain walls. Driving factor of this competition is ratio of the domain wall width to the crystal lattice parameter.

MAGNETIC RACE-TRACK — A NOVEL STORAGE CLASS SPINTRONIC MEMORY

2008 ◽  
Vol 22 (01n02) ◽  
pp. 117-118 ◽  
Author(s):  
STUART PARKIN
Keyword(s):  
Domain Wall ◽  
Tunnel Junction ◽  
Domain Walls ◽  
Magnetic Tunnel Junction ◽  
Domain Wall Motion ◽  
Wall Structure ◽  
Micromagnetic Simulations ◽  
Confining Potential ◽  
Current Pulses ◽  
Race Track

A proposal for a novel storage-class memory is described in which magnetic domains are used to store information in a "magnetic race-track".1 The magnetic race-track shift register storage memory promises a solid state memory with storage capacities and cost rivaling that of magnetic disk drives but with much improved performance and reliability. The magnetic race track is comprised of tall columns of magnetic material arranged perpendicularly to the surface of a silicon wafer. The domains are moved up and down the race-track by nanosecond long current pulses using the phenomenon of spin momentum transfer. The domain walls in the magnetic race-track are read using magnetic tunnel junction magnetoresistive sensing devices arranged in the silicon substrate. Recent progress in developing magnetic tunnel junction devices with giant tunneling magnetoresistance exceeding 350% at room temperature will be mentioned.2 Experiments exploring the current induced motion and depinning of domain walls in magnetic nano-wires with artificial pinning sites will be discussed. The domain wall structure, whether vortex or transverse, and the magnitude of the pinning potential is shown to have surprisingly little effect on the current driven dynamics of the domain wall motion.3 By contrast the motion of DWs under nanosecond long current pulses is surprisingly sensitive to their length.4 In particular, we find that the probability of dislodging a DW, confined to a pinning site in a permalloy nanowire, oscillates with the length of the current pulse, with a period of just a few nanoseconds. Using an analytical model and micromagnetic simulations we show that this behaviour is connected to a current induced oscillatory motion of the DW. The period is determined by the DW mass and the curvature of the confining potential. When the current is turned off during phases of the DW motion when the DW has enough momentum, there is a boomerang effect that can drive the DW out of the confining potential in the opposite direction to the flow of spin angular momentum. Note from Publisher: This article contains the abstract only.

Electrical Control of Magnetic Multi-Domain Transformation in a Specific Geometric-Patterned Ni Nanostructure on a Piezoelectric [Pb(Mg1/3Nb2/3)O3]0.68–[PbTiO3]0.32 Substrate

2016 ◽  
Author(s):  
Yu-Jen Chen ◽  
Tien-Kan Chung ◽  
Po-Jung Lin ◽  
Chiao-Fang Hung ◽  
Hou-Jen Chu ◽  
...  
Keyword(s):  
Domain Wall ◽  
Data Storage ◽  
Wall Motion ◽  
Domain Walls ◽  
Magnetoelectric Effect ◽  
Domain Wall Motion ◽  
Electrical Control ◽  
Domain State ◽  
Memory Applications ◽  
Domain Transformation

In this paper, we report an electrical control of magnetic multi-domain-walls transformation in an N-shape-patterned Ni nanostructures on a piezoelectric [Pb(Mg1/3Nb2/3)O3]0.68–[PbTiO3]0.32 substrate. Based on the converse-magnetoelectric-effect induced domain-wall transformation and the specific N-shape geometry guided domain-wall motion, the domain walls are successfully transformed by an applied electric field of 0.8 MV/m from the transverse domain wall state into the flux closure vortex domain state. These experimental results achieve the electrical control of multi-domain-walls transformation and would create more data storage and memory applications in the future.

Magnetic dipole interactions in dysprosium ethyl sulphate III. Magnetic and thermal properties below the Curie point

1968 ◽  
Vol 306 (1486) ◽  
pp. 335-353 ◽  
Keyword(s):  
Domain Wall ◽  
Magnetic Dipole ◽  
Wall Motion ◽  
Domain Walls ◽  
Domain Wall Motion ◽  
Single Spin ◽  
Relaxation Effects ◽  
Dipole Interactions ◽  
Spin Interactions ◽  
Spin Reversal

The thermal and magnetic properties of dysprosium ethyl sulphate have been measured at temperatures below its Curie temperature of 0⋅13 °K. The ferromagnetism is shown to be due almost entirely to magnetic dipole interactions which are highly anisotropic corresponding to a zero magnetic g -value perpendicular to the c -axis. The system thus approximates closely to a ferromagnetic Ising model. Because of demagnetizing effects the low field proper­ties are dominated by the formation of domains, which are shown to be long and thin with unusually abrupt domain walls. Measurements of the initial susceptibility at frequencies between 25 and 900 c/s show marked relaxation effects which are interpreted in terms of both domain wall motion and single spin reversals. A discussion is given of the general problem of finding the real and imaginary susceptibility components in systems with strong dipolar interactions. In favourable cases, such as dysprosium ethyl sulphate, it is possible to find a shape-independent quasi-static susceptibility which corresponds to the response of the system in the absence of domain wall motion and demagnetizing effects. Values for the spin-reversal relaxation time are found to be of the order of tens of microseconds which is surprisingly short in view of the absence of non-diagonal terms in the spin-spin interactions.

The behaviour of ferromagnetic sheets in alternating electric and magnetic fields I. A domain theory of the skin-effect impedance and complex permeability

1963 ◽  
Vol 276 (1364) ◽  
pp. 96-111 ◽  
Keyword(s):  
Domain Wall ◽  
Eddy Current ◽  
Short Range ◽  
Domain Walls ◽  
Domain Wall Motion ◽  
Domain Model ◽  
Complex Permeability ◽  
Low Frequencies ◽  
Domain Width ◽  
Wall Spacing

Eddy current losses measured in ferromagnetic materials are generally greatly in excess of values calculated on the usual assumption that the permeability is uniform throughout the material. In reality changes of magnetization occur, for the most part, within the relatively minute volume of the Bloch walls. In this paper a domain model consisting of nearly plane domain walls normal to the surfaces of an infinite sheet is adopted as a basis for the calculation of eddy current effects. The model is basically that of Polivanov (1952) but extended to include such effects as arise from the finite surface energy and inertia of the domain walls, relaxation damping of their motion, and short-range fluctuations in both domain width and the restoring forces which localize the walls. In addition to the dispersion of the complex effective permeability, the frequency dependence of the electrical resistance and inductance of a ferromagnetic strip are also calculated. At low frequencies the losses are found to be much higher, and at high frequencies somewhat lower, than the classically computed values, the disparity increasing with increasing wall spacing from zero at zero wall spacing. The effect of short-range fluctuations of the domain width is shown to be small, but similar fluctuations in the domain wall restoring pressure constant about its mean value are found to lead to very high losses at low frequencies coupled with high-frequency losses which are not much below those predicted by the classical theory, a result in agreement with experimental observation. It is shown also that theories based on this type of simple domain model, in which the intradomain permeability is neglected entirely in comparison with that attributed to domain wall motion, must eventually break down at frequencies so high that domain wall motions are effectively damped out and the eddy current behaviour is primarily governed by the small intra-domain permeability

scholarly journals Current-Driven Domain Wall Motion in Curved Ferrimagnetic Strips Above and Below the Angular Momentum Compensation

2021 ◽  
Vol 9 ◽  
Author(s):  
D. Osuna Ruiz ◽  
O. Alejos ◽  
V. Raposo ◽  
E. Martínez
Keyword(s):  
Angular Momentum ◽  
Domain Wall ◽  
High Speed ◽  
Wall Motion ◽  
Domain Walls ◽  
Relaxation Times ◽  
Domain Wall Motion ◽  
Current Density Distribution ◽  
Terminal Velocity ◽  
Artificial System

Current driven domain wall motion in curved Heavy Metal/Ferrimagnetic/Oxide multilayer strips is investigated using systematic micromagnetic simulations which account for spin-orbit coupling phenomena. Domain wall velocity and characteristic relaxation times are studied as functions of the geometry, curvature and width of the strip, at and out of the angular momentum compensation. Results show that domain walls can propagate faster and without a significant distortion in such strips in contrast to their ferromagnetic counterparts. Using an artificial system based on a straight strip with an equivalent current density distribution, we can discern its influence on the wall terminal velocity, as part of a more general geometrical influence due to the curved shape. Curved and narrow ferrimagnetic strips are promising candidates for designing high speed and fast response spintronic circuitry based on current-driven domain wall motion.

scholarly journals Bioelectrical signaling via domain wall migration

2019 ◽  
Author(s):  
Harold M. McNamara ◽  
Rajath Salegame ◽  
Ziad Al Tanoury ◽  
Haitan Xu ◽  
Shahinoor Begum ◽  
...  
Keyword(s):  
Domain Wall ◽  
Long Range ◽  
Domain Walls ◽  
Domain Wall Motion ◽  
Reaction Diffusion ◽  
Reaction Diffusion Equations ◽  
Membrane Voltage ◽  
Resting Potential ◽  
Stable Cell Line ◽  
Electrical Signaling

AbstractElectrical signaling in biology is typically associated with action potentials, transient spikes in membrane voltage that return to baseline. The Hodgkin-Huxley equations of electrophysiology belong to a more general class of reaction-diffusion equations which could, in principle, support patterns of membrane voltage which are stable in time but structured in space. Here we show theoretically and experimentally that homogeneous or nearly homogeneous tissues can undergo spontaneous spatial symmetry breaking into domains with different resting potentials, separated by stable bioelectrical domain walls. Transitions from one resting potential to another can occur through long-range migration of these domain walls. We map bioelectrical domain wall motion using all-optical electrophysiology in an engineered stable cell line and in human iPSC-derived myoblasts. Bioelectrical domain wall migration may occur during embryonic development and during physiological signaling processes in polarized tissues. These results demonstrate a novel form of bioelectrical pattern formation and long-range signaling.

scholarly journals Ionitronic manipulation of current-induced domain wall motion in synthetic antiferromagnets

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yicheng Guan ◽  
Xilin Zhou ◽  
Fan Li ◽  
Tianping Ma ◽  
See-Hun Yang ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Domain Wall ◽  
Wall Motion ◽  
Domain Walls ◽  
Magnetic Moments ◽  
Magnetic Layer ◽  
Ferromagnetic Layer ◽  
Domain Wall Motion ◽  
Antiferromagnetic Coupling ◽  
Induced Motion

AbstractThe current induced motion of domain walls forms the basis of several advanced spintronic technologies. The most efficient domain wall motion is found in synthetic antiferromagnetic (SAF) structures that are composed of an upper and a lower ferromagnetic layer coupled antiferromagnetically via a thin ruthenium layer. The antiferromagnetic coupling gives rise to a giant exchange torque with which current moves domain walls at maximum velocities when the magnetic moments of the two layers are matched. Here we show that the velocity of domain walls in SAF nanowires can be reversibly tuned by several hundred m/s in a non-volatile manner by ionic liquid gating. Ionic liquid gating results in reversible changes in oxidation of the upper magnetic layer in the SAF over a wide gate-voltage window. This changes the delicate balance in the magnetic properties of the SAF and, thereby, results in large changes in the exchange coupling torque and the current-induced domain wall velocity. Furthermore, we demonstrate an example of an ionitronic-based spintronic switch as a component of a potential logic technology towards energy-efficient, all electrical, memory-in-logic.

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