Model for domain wall avalanches in ferromagnetic thin films

Buceta, R. C.; Muraca, Diego

doi:10.1016/j.physa.2011.06.071

Cited by 7 publications

(6 citation statements)

References 46 publications

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“…n ′ j = max(n j−1 , n j , n j+1 )). These rules applied over a lattice with randomly distributed defects lead to the same properties as those obtained by the BM model: avalanches and scaling anomalies, with similar quantitative conclusions [6,49].…”

Section: The Modelsupporting

confidence: 67%

“…Systems with magnetic avalanches are classified by measuring the power-law exponents [2] of the Barkhausen distributions of avalanche size τ and duration α, and the average of avalanche size as a function of the avalanche duration ανz 1/ , and/or the power spectrum ϑ. The studies have led us to accept that there are two universality classes [2][3][4][5][6] associated with the range of the dominant interactions (dipolar or exchange), which prevail in amorphous and polycrystalline materials, respectively. For materials that exhibit three-dimensional magnetic behaviour (bulk materials including ribbons and sheets) these two universality classes have been accepted, even when the experimental values of the exponents were widely dispersed within each class.…”

Section: Introductionmentioning

confidence: 99%

“…Figure 1: (Color online) Left: log-log plot of the average saturation velocity v sat as a function of the reduced force f = p/p c − 1 close to the depinning transition, with p c ≃ p * = 0.88716. The measured exponent is θ = 0.0376(6) (see Table1). Right: log-log plot of the saturation global interface width W sat as a function of the reduced force f close to the depinning transition.…”

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confidence: 99%

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Scaling properties of a ferromagnetic thin film model at the depinning transition

Torres¹,

Buceta²

2015

J. Stat. Mech.

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In this paper, we perform a detailed study of the scaling properties of a ferromagnetic thin film model. Recently, interest has increased in the scaling properties of the magnetic domain wall (MDW) motion in disordered media when an external driving field is present. We consider a (1+1)-dimensional model, based on evolution rules, able to describe the MDW avalanches. The global interface width of this model shows Family-Vicsek scaling with roughness exponent ζ ≃ 1.585 and growth exponent β ≃ 0.975. In contrast, this model shows scaling anomalies in the interface local properties characteristic of other systems with depinning transition of the MDW, e.g. quenched Edwards-Wilkinson (QEW) equation and random-field Ising model (RFIM) with driving. We show that, at the depinning transition, the saturated average velocity v sat ∼ f θ vanished very slowly (with θ ≃ 0.037) when the reduced force f = p/p c −1 → 0 + . The simulation results show that this model verifies all accepted scaling relations which relate the global exponents and the correlation length (or time) exponents, valid in systems with depinning transition. Using the interface tilting method, we show that the model, close to the depinning transition, exhibits a nonlinearity similar to the one included in the Kardar-Parisi-Zhang (KPZ) equation. The nonlinear coefficient λ ∼ f −φ with φ ≃ −1.118, which implies that λ → 0 as the depinning transition is approached, a similar qualitatively behaviour to the driven RFIM. We conclude this work by discussing the main features of the model and the prospects opened by it.

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Section: The Modelsupporting

confidence: 67%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Scaling properties of a ferromagnetic thin film model at the depinning transition

Torres¹,

Buceta²

2015

J. Stat. Mech.

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“…The sleep-and wakestage distributions show similar behaviours to those described for tumble and run respectively: the disruptive-sleep duration follows exponential distributions, while the wake duration is selforganized with power-laws distributions [31]. These behaviours resemble the dynamics seen in some models of self-organized criticality (SOC): avalanche-time distributions follow power laws, while quiessence-time distributions can be exponential [32]. However, our system is out of criticality, since the mean runtime is finite.…”

Section: Internal Signaling Systemsupporting

confidence: 57%

Stochastic model for the CheY-P molarity in the neighbourhood ofE. coliflagella motors

Fier

Hansmann

Buceta

2019

Preprint

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Escherichia coli serves as prototype for the study of peritrichous enteric bacteria that perform runs and tumbles alternately. Bacteria run forward as a result of the counterclockwise (CCW) rotation of their flagella bundle, which is located rearward, and perform tumbles when at least one of their flagella rotates clockwise (CW), moving away from the bundle. The flagella are hooked to molecular rotary motors of nanometric diameter able to make transitions between CCW and CW rotations that last up to one hundredth of a second. At the same time, flagella move or rotate the bacteria's body microscopically during lapses that range between a tenth and ten seconds. We assume that the transitions between CCW and CW rotations occur solely by fluctuations of CheY-P molarity in the presence of two threshold values, and that a veto rule selects the run or tumble motions. We present Langevin equations for the CheY-P molarity in the vicinity of each molecular motor. This model allows to obtain the run-or tumble-time distribution as a linear combination of decreasing exponentials that is a function of the steady molarity of CheY-P in the neighbourhood of the molecular motor, which fits experimental data. In turn, if the internal signaling system is unstimulated, we show that the runtime distributions reach power-law behaviour, a characteristic of self-organized systems, in some time range and, afterwards, exponential cutoff. In addition, our model explains without any fitting parameters the ultrasensitivity of the flagella motors as a function of the steady state of CheY-P molarity. In addition, we show that the tumble bias for peritrichous bacterium has a similar sigmoid-shape to the CW bias, although shifted to lower concentrations when the flagella number increases. Thus, the increment in the flagella number allows lower operational values for each motor increasing amplification and robustness of the chemotatic signaling pathway. * David.Hansmann@conicet.gov.ar † rbuceta@mdp.edu.ar

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“…For two-dimensional systems and samples with reduced dimensions, the BN statistical properties are less clear. On the theoretical side, models and simulations [32][33][34][35][36][37][38][39][40][41] infer the existence of two distinct universality classes, according the range of interactions governing the DWs dynamics, as well as indicate that three and two-dimensional systems present distinct exponents.…”

Section: Introductionmentioning

confidence: 99%

Statistical properties of Barkhausen noise in amorphous ferromagnetic films

et al. 2014

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We investigate the statistical properties of the Barkhausen noise in amorphous ferromagnetic films with thicknesses in the range between 100 and 1000 nm. From Barkhausen noise time series measured with the traditional inductive technique, we perform a wide statistical analysis and establish the scaling exponents τ , α, 1/σνz, and ϑ. We also focus on the average shape of the avalanches, which gives further indications on the domain wall dynamics. Based on experimental results, we group the amorphous films in a single universality class, characterized by scaling exponents τ ∼ 1.27, α ∼ 1.5, 1/σνz ∼ ϑ ∼ 1.77, values similar to that obtained for several bulk amorphous magnetic materials. Besides, we verify that the avalanche shape depends on the universality class. By considering the theoretical models for the dynamics of a ferromagnetic domain wall driven by an external magnetic field through a disordered medium found in literature, we interpret the results and identify an experimental evidence that these amorphous films, within this thickness range, present a typical three-dimensional magnetic behavior with predominant short-range elastic interactions governing the domain wall dynamics. Moreover, we provide experimental support for the validity of a general scaling form for the average avalanche shape for non-mean-field systems.

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Model for domain wall avalanches in ferromagnetic thin films

Cited by 7 publications

References 46 publications

Scaling properties of a ferromagnetic thin film model at the depinning transition

Scaling properties of a ferromagnetic thin film model at the depinning transition

Stochastic model for the CheY-P molarity in the neighbourhood ofE. coliflagella motors

Statistical properties of Barkhausen noise in amorphous ferromagnetic films

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