Dynamic interaction between domain walls and nanowire vertices

Burn, D. M.; Chadha, Megha; Walton, S. K.; Branford, W. R.

doi:10.1103/physrevb.90.144414

Cited by 25 publications

(26 citation statements)

References 29 publications

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“…With increasing applied field the DW approaches the vertex, undergoes a micromagnetic structural rearrangement during it's interaction, eventually de-pinning at a de-pinning field which is discussed in detail elsewhere. 13 The angular dependence to this depinning field is shown in figure 7 for both up-and downchirality DWs where an asymmetry about the wire axis originates from the chirality of the DW.…”

Section: Resultsmentioning

confidence: 99%

“…Such measurements are performed using more complex applied field protocol involving rotating fields in the plane of the sample. 13,19 Figure 6 shows the angular dependence to the reversal field measured for the 70 nm wide bars with an initial asymmetrical magnetization distribution at the vertex as illustrated in the figure. Again a 60 • rotation symmetry is observed relating to the rotational symmetry of the structure.…”

Section: Resultsmentioning

confidence: 99%

“…10 The field driven manipulation of pre-existing DWs in connected artificial spin ice systems is governed by the chirality and topological nature of the DW 11,12 and it's time-evolution during dynamic propagation. 13,14 These DWs typically originate at the edges of the sample as the reversal in the center of the array is constrained by the magnetization of the surrounding bars. 15 Therefore, the magnetization reversal in one bar triggers the reversal in neighbouring bars and leads to chains of reversal following Dirac strings in avalanche-like behavior.…”

Section: Introductionmentioning

confidence: 99%

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Angular-dependent magnetization reversal processes in artificial spin ice

2015

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The angular dependence to the magnetization reversal in interconnected kagome artificial spin ice structures has been studied through experimental MOKE measurements and micromagnetic simulations. This reversal is mediated by the propagation of magnetic domain walls along the interconnecting bars which either nucleate at the vertex or arrive following an interaction in a neighbouring vertex. The physical differences in these processes show a distinct angular dependence allowing the different contributions to be identified. The configuration of the initial magnetization state, either locally or on a full sublattice of the system, controls the reversal characteristics of the array within a certain field window. This shows how the available magnetization reversal routes can be manipulated and the system trained.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Angular-dependent magnetization reversal processes in artificial spin ice

2015

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“…The shape anisotropy of each nanobar forces its magnetization to lie in one of two directions along its long axis and so it acts as an 'ising macrospin'. The term ASI was originally applied to a square array of electrically and magnetically isolated bars [3], but here we consider continuous honeycomb or kagome ASI structures [4][5][6][7][8][9][10][11][12][13][14][15][16]. In the honeycomb three of these ising macrospins meet at each vertex and their interactions are governed by a set of 'ice rules', which minimize the local magnetic charge at each vertex without favouring a specific spin structure.…”

Section: Introductionmentioning

confidence: 99%

Limitations in artificial spin ice path selectivity: the challenges beyond topological control

et al. 2015

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Magnetic charge is carried through nanowire networks by domain walls, and the micromagnetic structure of a domain wall provides an opportunity to manipulate its movement. We have shown previously that magnetic monopole defects exist in artificial spin ice (ASI) and result from two bar switching at a vertex. To create and manipulate monopole defects and indeed magnetic charge in general, path selectivity of the domain wall at a vertex is required. We have recently shown that in connected ASI structures, transverse wall chirality (or topology) determines wall path direction, but a mechanism known as Walker breakdown, where a wall mutates into a wall of opposite chirality partially destroys selectivity. Recently it has been claimed that in isolated Y-shaped junctions that support vortex walls, selectivity is entirely determined by chirality (or topology), the suggestion being that vortex wall chirality is robust in the Walker breakdown process. Here we demonstrate that in Yshaped junctions, magnetic switching in the important topologically protected regime exists only for a narrow window of field and bar geometry, and that it will be challenging to access this regime in fielddriven ASI. This work has implications for the wider field of magnetic charge manipulation for high density memory storage.

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“…In contrast to the already studied open-loop DW based device structure 16,17 , this alternative concept includes a different geometrical feature, namely a cross-shaped intersection of nanowires, which has been investigated numerically and experimentally 15,[18][19][20][21] . This geometry ultimately enables a disruptive device that can count millions of turns.…”

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confidence: 99%

Geometrically enhanced closed-loop multi-turn sensor devices that enable reliable magnetic domain wall motion

Borie

Wahrhusen²,

Grimm³

et al. 2017

Applied Physics Letters

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We experimentally realize a sophisticated structure geometry for reliable magnetic domain wall-based multiturn-counting sensor devices, which we term closed-loop devices that can sense millions of turns. The concept relies on the reliable propagation of domain walls through a cross-shaped intersection of magnetic conduits, to allow the intertwining of loops of the sensor device. As a key step to reach the necessary reliability of the operation, we develop a combination of tilted wires called the syphon structure at the entrances of the cross. We measure the control and reliability of the domain wall propagation individually for cross-shaped intersections, the syphon geometries and finally combinations of the two for various field configurations (strengths and angles). The various measured syphon geometries yield a dependence of the domain wall propagation on the shape that we explain by the effectively acting transverse and longitudinal external applied magnetic fields. The combination of both elements yields a behaviour that cannot be explained by a simple superposition of the individual different maximum field operation values. We identify as an additional process the nucleation of domain walls in the cross, which then allows us to fully gauge the operational parameters. Finally, we demonstrate that by tuning the central dimensions of the cross and choosing the optimum angle for the syphon structure reliable sensor operation is achieved, which paves the way for disruptive multi-turn sensor devices.

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Dynamic interaction between domain walls and nanowire vertices

Cited by 25 publications

References 29 publications

Angular-dependent magnetization reversal processes in artificial spin ice

Angular-dependent magnetization reversal processes in artificial spin ice

Limitations in artificial spin ice path selectivity: the challenges beyond topological control

Geometrically enhanced closed-loop multi-turn sensor devices that enable reliable magnetic domain wall motion

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