Dynamic switching of the spin circulation in tapered magnetic nanodisks

Uhlíř, Vojtěch; Urbánek, Michal; Hladík, L.; Spousta, J.; Im, Mi‐Young; Fischer, Peter; Eibagi, Nasim; Kan, Jimmy J.; Fullerton, Eric E.; Šikola, Tomáš

doi:10.1038/nnano.2013.66

Cited by 112 publications

(76 citation statements)

References 52 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The vortex state can be controlled by applying a static out-of-plane (polarity control 8 ) or in-plane (circulation control 9 ) magnetic fields, although the amplitude of these fields can be quite large. However, both the polarity and the circulation can be switched more effectively by using fast-rising magnetic fields 10,11 .…”

Section: Introductionmentioning

confidence: 99%

“…We have recently demonstrated 11 , that this can be achieved by using a fast rising in-plane magnetic field pulse that drives the vortex core into far-from-equilibrium gyrotropic precession and annihilates the vortex during the first half-period of the precessional motion at the disk boundary. The resulting circulation of a new vortex is controlled by a disk asymmetry in the form of a thickness gradient and by the direction of the magnetic field pulse.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Dynamics and efficiency of magnetic vortex circulation reversal

et al. 2015

View full text Add to dashboard Cite

Dynamic switching of the vortex circulation in magnetic nanodisks by fast rising magnetic field pulse requires annihilation of the vortex core at the disk boundary and reforming a new vortex with the opposite sense of circulation. Here we study the influence of pulse parameters on the dynamics and efficiency of the vortex core annihilation in permalloy (Ni80Fe20) nanodisks. We use magnetic transmission soft x-ray microscopy to experimentally determine a pulse rise time -pulse amplitude phase diagram for vortex circulation switching and investigate the time-resolved evolution of magnetization in different regions of the phase diagram. The experimental phase diagram is compared with an analytical model based on Thiele's equation describing high amplitude vortex core motion in a parabolic potential. We find that the analytical model is in a good agreement with experimental data for a wide range of disk geometries. From the outputs of the analytical model and in accordance with our experimental finding we determine the geometrical condition for dynamic vortex core annihilation and pulse parameters needed for the most efficient and fastest circulation switching. The comparison of our experimental results with micromagnetic simulations show that the micromagnetic simulations of 'ideal' disks with diameters larger than ∼250 nm overestimate nonlinearities in susceptibility and eigenfrequency. This overestimation leads to the core polarity switching near the disk boundary, which then in disagreement with experimental findings prevents the core annihilation and circulation switching. We modify the micromagnetic simulations by introducing the 'boundary region' of reduced magnetization to simulate the experimentally determined susceptibility and in these modified micromagnetic simulations we are able to reproduce the experimentally observed dynamic vortex core annihilation and circulation switching.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Dynamics and efficiency of magnetic vortex circulation reversal

et al. 2015

View full text Add to dashboard Cite

show abstract

“…Vortex gyration, which can be induced by magnetic or current field pulses in confined magnetic elements, such as circles, squares, ellipses and rectangles are perfectly repeatable and suited for that. Controlling both the polarity, i.e., the vortex core orientation [35] and the circularity, i.e., the sense of rotation of the in-plane spin configuration [36] was demonstrated, although details in these processes, which occur on much faster time scales, are still experimentally inaccessible with current x-ray microscopies. The dynamics of stochastic or non-deterministic processes, which are the more general case for spin dynamics is still not accessible either.…”

Section: What Has Been Achieved So Far With Magnetic X-ray Microscopimentioning

confidence: 99%

Frontiers in imaging magnetism with polarized x-rays

Fischer

2015

Front. Phys.

View full text Add to dashboard Cite

Although magnetic imaging with polarized x-rays is a rather young scientific discipline, the various types of established x-ray microscopes have already taken an important role in state-of-the-art characterization of the properties and behavior of spin textures in advanced materials. The opportunities ahead will be to obtain in a unique way indispensable multidimensional information of the structure, dynamics and composition of scientifically interesting and technologically relevant magnetic materials.Keywords: X-ray spectromicroscopy, Fresnel zone plates, spin dynamics, nanomagnetism, x-ray magnetic circular dichroism Although magnetism is among the oldest physical phenomena known to mankind, the magnetic properties of condensed matter continue to be among the most exciting scientific topics in solid state physics. Magnetism is the backbone of numerous current and future technologies having penetrated our daily life. Applications involving magnetic materials range from nanoscale devices in spintronics [1] that have revolutionized information and sensor technologies to large permanent magnets [2] critical to power generation, transmission and conversion and transportation, e.g., with electric vehicles. Despite this massive technological use of magnetic materials, a fundamental understanding of magnetism, which would allow predicting e.g., a lightweight, sustainable and high performing material for permanent magnets, is still missing.From the scientific point of view, it is the spin of the electron and the coupling and competing interactions of all spins in a system, which constitutes the fundamental theoretical concept to describe magnetism and magnetic behavior. The exchange interaction is the strongest interaction and favors either parallel or antiparallel alignment of the spins thus giving rise to ferroor antiferromagnetism. The spin-orbit interaction is currently a topic of paramount current interest to the magnetism community, specifically as novel effects occur, when e.g., 3d transition metals such as Fe, Co, Ni are interfaced with high Z materials, e.g., Pt, Ta, thus adding a large spin-orbit coupling. Chiral interactions, such as the Dzyaloshinkii-Moriya interaction, favor non-collinear spin arrangements, and introduces e.g., a certain handedness, which not only gives rise to topologically protected spin textures such as skyrmions, but impacts also, e.g., domain wall motion in nanowires [3].The magnetic anisotropy prefers certain orientation of the spins and therefore ultimately enables concepts e.g., to store magnetic information. One of the problems in magnetic recording is that higher anisotropy magnetic materials are needed to increase thermal stability. On the other hand, a higher anisotropy requires increased magnetic fields for magnetization reversal, which has engineering limitations. The most promising path to bypass this trilemma is heat assisted magnetic recording [4], where temporarily the anisotropy is locally reduced by heating thus allowing for switching locally the magnetization with much...

show abstract

“…The magnetic vortex is characterized by an in-plane circulating domain structure, the circularity c, which rotates either clockwise (CW, c ¼ þ 1) or counter-clockwise (CCW, c ¼ À 1) and an out-of-plane magnetization, the polarity p pointing either up (p ¼ þ 1) or down (p ¼ À 1) [12][13][14][15][16][17][18] . In the context of skyrmions, the magnetic vortex structure (VS) can be described by a topological charge, the skyrmion number of np/2 ¼ ±1/2 with the winding number of n ¼ H [a (f)/2p]dS ¼ þ 1 (refs 19-21).…”

mentioning

confidence: 99%

Stochastic formation of magnetic vortex structures in asymmetric disks triggered by chaotic dynamics

Lee

Vogel

et al. 2014

Nat Commun

View full text Add to dashboard Cite

The non-trivial spin configuration in a magnetic vortex is a prototype for fundamental studies of nanoscale spin behaviour with potential applications in magnetic information technologies. Arrays of magnetic vortices interfacing with perpendicular thin films have recently been proposed as enabler for skyrmionic structures at room temperature, which has opened exciting perspectives on practical applications of skyrmions. An important milestone for achieving not only such skyrmion materials but also general applications of magnetic vortices is a reliable control of vortex structures. However, controlling magnetic processes is hampered by stochastic behaviour, which is associated with thermal fluctuations in general. Here we show that the dynamics in the initial stages of vortex formation on an ultrafast timescale plays a dominating role for the stochastic behaviour observed at steady state. Our results show that the intrinsic stochastic nature of vortex creation can be controlled by adjusting the interdisk distance in asymmetric disk arrays.

show abstract

Dynamic switching of the spin circulation in tapered magnetic nanodisks

Cited by 112 publications

References 52 publications

Dynamics and efficiency of magnetic vortex circulation reversal

Dynamics and efficiency of magnetic vortex circulation reversal

Frontiers in imaging magnetism with polarized x-rays

Stochastic formation of magnetic vortex structures in asymmetric disks triggered by chaotic dynamics

Contact Info

Product

Resources

About