Reduced stochasticity in domain wall motion with increasing pinning density in thin Fe films

Lee, Hun-Sung; Ryu, Kwang-Su; You, Chun‐Yeol; Jeon, Kun-Rok; Parkin, S. S. P.; Shin, Sung‐Chul

doi:10.1088/1367-2630/13/8/083038

Cited by 10 publications

(10 citation statements)

References 33 publications

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“…Some results indicate that the shape of the sample becomes increasingly relevant with the reduced dimensionality [9]. Moreover, the new visualisation techniques provide a direct observation of the domain-wall motion in different experimental settings [4,[10][11][12][13][14][15]; these experiments disclose important details of the stochastic dynamics and avalanching behaviour. For instance, the studies in [4,11] reveal the domain-evolution patterns in ferromagnetic MnAs and Co films using time-resolved magneto-optical microscopy.…”

Section: Introductionmentioning

confidence: 98%

Dynamical implications of sample shape for avalanches in 2-dimensional random-field Ising model with saw-tooth domain wall

Tadić

2018

Physica A: Statistical Mechanics and its Applications

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We study dynamics of a built-in domain wall (DW) in 2-dimensional disordered ferromagnets with different sample shapes using random-field Ising model on a square lattice rotated by 45 degrees. The saw-tooth DW of the length L x is created along one side and swept through the sample by slow ramping of the external field until the complete magnetisation reversal and the wall annihilation at the open top boundary at a distance L y . By fixing the number of spins N = L x × L y = 10 6 and the random-field distribution at a value above the critical disorder, we vary the ratio of the DW length to the annihilation distance in the range L x /L y ∈ [1/16, 16]. The periodic boundary conditions are applied in the y-direction so that these ratios comprise different samples, i.e., surfaces of cylinders with the changing perimeter L x and height L y . We analyse the avalanches of the DW slips between following field updates, and the multifractal structure of the magnetisation fluctuation time series. Our main findings are that the domain-wall lengths materialised in different sample shapes have an impact on the dynamics at all scales. Moreover, the domain-wall motion at the beginning of the hysteresis loop (HLB) probes the disorder effects resulting in the fluctuations that are significantly different from the large avalanches in the central part of the loop (HLC), where the strong fields dominate. Specifically, the fluctuations in HLB exhibit a wide multi-fractal spectrum, which shifts towards higher values of the exponents when the DW length is reduced. The distributions of the avalanches in this segments of the loops obey power-law decay and the exponential cutoffs with the exponents firmly in the mean-field universality class for long DW. In contrast, the avalanches in the HLC obey Tsallis density distribution with the power-law tails which indicate the new categories of the scale invariant behaviour for different ratios L x /L y . The large fluctuations in the HLC, on the other hand, have a rather narrow spectrum which is less sensitive to the length of the wall. These findings shed light to the dynamical criticality of the random-field Ising model at its lower critical dimension; they can be relevant to applications of the dynamics of injected domain walls in two-dimensional nanowires and ferromagnetic films.

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Section: Introductionmentioning

confidence: 98%

Dynamical implications of sample shape for avalanches in 2-dimensional random-field Ising model with saw-tooth domain wall

Tadić

2018

Physica A: Statistical Mechanics and its Applications

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“…Additionally, the reversal patterns are quite different upon each measurement, showing random behavior with respect to the interval, size, and location, which is one of the most important characteristics of Barkhausen avalanches. 24,25 The jump size distribution also confirms that magnetization reversal in the backward branch occurs via a Barkhausen avalanche dominant mode. As shown in Fig.…”

Section: Resultsmentioning

confidence: 57%

“…3, showing behavior similar to that of a random Barkhausen avalanche dominant reversal mode. 24,25 The major origin of this phenomenon is the enhanced degree of magnetic disorder during the backward branch reversal process. As mentioned earlier, forward branch reversal occurs via thermally activated depinning from a single potential barrier, indicating that the energy barrier is nearly equal throughout the sample area.…”

Section: Resultsmentioning

confidence: 99%

“…[6][7][8][9][10][11][12][13][14] One of the most interesting and unsolved issues pertaining to the magnetization reversal behavior of an exchange-biased F layer is whether asymmetry exists in the stochastic nature of the domain wall (DW) dynamics between both branches of a hysteresis loop. It is generally known that DW motion in an F layer reveals stochastic behavior [15][16][17][18][19][20][21][22][23][24][25] due to randomly distributed defects that exist within samples, which generally act as DW pinning sites during the magnetization reversal process. Considering the fact that the magnetization reversal behavior in an exchange-biased system is quite different between the two branches of a hysteresis loop, 7,[9][10][11] one can expect that such an asymmetry will have an influence on the stochastic nature of the magnetization reversal process.…”

Section: Introductionmentioning

confidence: 99%

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Asymmetric stochasticity of magnetization reversal dynamics in exchange-biased IrMn/CoFe Film

Lee

Ryu

You

et al. 2012

Journal of Applied Physics

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In this study, we investigated the stochastic nature of domain reversal dynamics in exchange-biased IrMn/CoFe film using a time-resolved Kerr microscope. Interestingly, the statistical distributions of the magnetization half-reversal times for both forward and backward applied fields show that the magnetization reversal dynamics is much more stochastic for the backward branch, where an applied field is parallel to the exchange-bias field direction. The enhanced stochasticity is ascribed to the large degree of magnetic disorder during backward reversal, which induces discrete and random Barkhausen jumps, whereas the forward branch reversal is dominated by a thermally activated depinning process caused by a single potential barrier. This result can be explained by the asymmetry of the magnetic disorder between both branches of a hysteresis loop. V

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“…1(c), indicating that DWs can be pinned at the hard axis corners without the preferred selection of the arm switching between Q and R(CCW direction). The microstructural defects from the fabrication process would induce different depinning strength from both long axis corners in the switching process [19]. Fig.…”

Section: Resultsmentioning

confidence: 99%

Domain wall movement in a rhombic Co thin film ring

Nam

Körner

Ross

2015

Current Applied Physics

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Reduced stochasticity in domain wall motion with increasing pinning density in thin Fe films

Cited by 10 publications

References 33 publications

Dynamical implications of sample shape for avalanches in 2-dimensional random-field Ising model with saw-tooth domain wall

Dynamical implications of sample shape for avalanches in 2-dimensional random-field Ising model with saw-tooth domain wall

Asymmetric stochasticity of magnetization reversal dynamics in exchange-biased IrMn/CoFe Film

Domain wall movement in a rhombic Co thin film ring

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