Effect of Dipolar Interactions for Domain-Wall Dynamics in Magnetic Thin Films

Mughal, Adil; Laurson, Lasse; Durin, Gianfranco; Zapperi, Stefano

doi:10.1109/tmag.2009.2033552

Cited by 16 publications

(18 citation statements)

References 9 publications

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“…Summarizing the theoretical predictions, for three-dimensional systems with the dynamics governed by long-range interactions, the scaling exponents are τ = 1.50, α = 2.0 and 1/σνz = 2 [54,55], while for systems governed by short-range interactions and same dimensionality, τ = 1.27, α = 1.5 and 1/σνz = 1.77 [36,37,54,55]. On the other side, for two-dimensional systems, although there is not a complete agreement between theoreticians on the real values, the models indicate τ ∼ 1.33, α ∼ 1.5 and 1/σνz ∼ 1.5 for the long-range interaction problem [32][33][34]77], while τ ∼ 1.06 for the short-range interaction one [36,37,77]. In the last case, α and 1/σνz are still not predicted.…”

Section: B Barkhausen Noise and Statistical Propertiesmentioning

confidence: 94%

“…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%

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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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Section: B Barkhausen Noise and Statistical Propertiesmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Statistical properties of Barkhausen noise in amorphous ferromagnetic films

et al. 2014

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“…It was argued that by varying T close to T c , one can tune the value of the squared saturation magnetization M 2 s , and thus the strength of the long-range dipolar interactions between different DW segments. The zigzag pattern is expected to arise as a result of a competition between the domain-wall energy and the dipolar interactions, with the former favoring a flat horizontal DW, while the latter would prefer a vertically spread DW to reduce the magnetic charge density [15][16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Universality classes and crossover scaling of Barkhausen noise in thin films

2014

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We study the dynamics of head-to-head domain walls separating in-plane domains in a disordered ferromagnetic thin film. The competition between the domain-wall surface tension and dipolar interactions induces a crossover between a rough domain-wall phase at short length scales and a large-scale phase where the walls display a zigzag morphology. The two phases are characterized by different critical exponents for Barkhausen avalanche dynamics that are in quantitative agreement with experimental measurements on MnAs thin films.

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“…Their role in the physics of the Barkhausen effect needs to be studied. The typical models of Barkhausen noise, such as elastic interfaces in random media [4,14], scalar field models [15] or the random field Ising model (RFIM) [16][17][18], exclude BLs by construction.Here, we focus on understanding the consequences of the presence of BLs within DWs on the jerky DW motion through a disordered thin ferromagnetic film. To this end, we study field-driven DW dynamics considering as a test system a 0.5 nm thick Co film within a Pt/Co/Pt multilayer [19] with perpendicular magnetic anisotropy (PMA) by micromagnetic simulations, able to fully capture the DW internal structure.…”

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confidence: 99%

Barkhausen Noise from Precessional Domain Wall Motion

Herranen

Laurson

2019

Phys. Rev. Lett.

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The jerky dynamics of domain walls driven by applied magnetic fields in disordered ferromagnets -the Barkhausen effect -is a paradigmatic example of crackling noise. We study Barkhausen noise in disordered Pt/Co/Pt thin films due to precessional motion of domain walls using full micromagnetic simulations, allowing for a detailed description of the domain wall internal structure. In this regime the domain walls contain topological defects known as Bloch lines which repeatedly nucleate, propagate and annihilate within the domain wall during the Barkhausen jumps. In addition to bursts of domain wall propagation, the in-plane Bloch line dynamics within the domain wall exhibits crackling noise, and constitutes the majority of the overall spin rotation activity.Understanding the bursty crackling noise response of elastic objects in random media -domain walls (DWs) [1], cracks [2], fluids fronts invading porous media [3], et cetera -to slowly varying external forces is one of the main problems of statistical physics of materials. An important example is given by the magnetic field driven dynamics of DWs in disordered ferromagnets, where they respond to a slowly changing external magnetic field by exhibiting a sequence of discrete jumps with a power-law size distribution [1,4]. This phenomenon, known as the Barkhausen effect [5], has been studied extensively, and a fairly well-established picture of the possible universality classes of the avalanche dynamics, using the language of critical phenomena, is emerging [1,4].Magnetic DWs constitute a unique system exhibiting crackling noise since the driving field may, in addition to pushing the wall forward, excite internal degrees of freedom within the DW [6]. This effect is well-known especially in the nanowire geometry -important for the proposed spintronics devices such as the racetrack memory [7] -where the onset of precession of the DW magnetization above a threshold field leads to an abrupt drop in the DW propagation velocity (the Walker breakdown [8]), and hence to a non-monotonic driving field vs DW velocity relation [9]; these features are well-captured by the so-called 1d models [10].In wider strips or thin films, the excitations of the DW internal magnetization accompanying the velocity drop cannot be described by precession of an individual magnetic moment. Instead, one needs to consider the nucleation, propagation and annihilation of topological defects known as Bloch lines (BLs) within the DW [11][12][13]. BLs, i.e., transition regions separating different chiralities of the DW, have been studied in the context of bubble materials already in the 1970's [13]. Their role in the physics of the Barkhausen effect needs to be studied. The typical models of Barkhausen noise, such as elastic interfaces in random media [4,14], scalar field models [15] or the random field Ising model (RFIM) [16][17][18], exclude BLs by construction.Here, we focus on understanding the consequences of the presence of BLs within DWs on the jerky DW motion through a disordered thin ferromagne...

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Effect of Dipolar Interactions for Domain-Wall Dynamics in Magnetic Thin Films

Cited by 16 publications

References 9 publications

Statistical properties of Barkhausen noise in amorphous ferromagnetic films

Statistical properties of Barkhausen noise in amorphous ferromagnetic films

Universality classes and crossover scaling of Barkhausen noise in thin films

Barkhausen Noise from Precessional Domain Wall Motion

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