Universality classes and crossover scaling of Barkhausen noise in thin films

Laurson, Lasse; Durin, Gianfranco; Zapperi, Stefano

doi:10.1103/physrevb.89.104402

Cited by 16 publications

(19 citation statements)

References 32 publications

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“…In other words, although there is spatial localization of strain, we do not observe complete dimensional reduction for either kernel. Intriguingly, recent simulation studies [37] …”

Section: Discussionmentioning

confidence: 97%

Avalanche localization and crossover scaling in amorphous plasticity

Budrikis

Zapperi

2013

Phys. Rev. E

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We perform large-scale simulations of a two-dimensional lattice model for amorphous plasticity with random local yield stresses and long-range quadrupolar elastic interactions. We show that as the external stress increases towards the yielding phase transition, the scaling behavior of the avalanches crosses over from mean-field theory to a different universality class. This behavior is associated with strain localization, which significantly depends on the short-range properties of the interaction kernel.

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“…In other words, although there is spatial localization of strain, we do not observe complete dimensional reduction for either kernel. Intriguingly, recent simulation studies [37] …”

Section: Discussionmentioning

confidence: 97%

Avalanche localization and crossover scaling in amorphous plasticity

Budrikis

Zapperi

2013

Phys. Rev. E

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“…In particular, it would allow to address the question of the possible relevance of the DW internal structure, including VBLs and HBLs, on the nature of the jerky, avalanche-like DW motion observed in the context of the Barkhausen effect 34 . Most often such dynamics have been modeled by describing the DWs as elastic interfaces in random media, with the details of the interaction kernel depending on whether the long-range dipolar interactions are thought to be relevant or not 35,36 . However, in such models the dynamical internal structure of the DW is neglected, and it is a pertinent question if such an approximation is valid in all cases.…”

Section: Discussionmentioning

confidence: 99%

Bloch-line dynamics within moving domain walls in 3D ferromagnets

Herranen

Laurson

2017

Phys. Rev. B

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We study field-driven magnetic domain wall dynamics in garnet strips by large-scale threedimensional micromagnetic simulations. The domain wall propagation velocity as a function of the applied field exhibits a low-field linear part terminated by a sudden velocity drop at a threshold field magnitude, related to the onset of excitations of internal degrees of freedom of the domain wall magnetization. By considering a wide range of strip thicknesses from 30 nm to 1.89 µm, we find a non-monotonic thickness dependence of the threshold field for the onset of this instability, proceeding via nucleation and propagation of Bloch lines within the domain wall. We identify a critical strip thickness above which the velocity drop is due to nucleation of horizontal Bloch lines, while for thinner strips and depending on the boundary conditions employed, either generation of vertical Bloch lines, or close-to-uniform precession of the domain wall internal magnetization takes place. For strips of intermediate thicknesses, the vertical Bloch lines assume a deformed structure due to demagnetizing fields at the strip surfaces, breaking the symmetry between the top and bottom faces of the strip, and resulting in circulating Bloch line dynamics along the perimeter of the domain wall.

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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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Universality classes and crossover scaling of Barkhausen noise in thin films

Cited by 16 publications

References 32 publications

Avalanche localization and crossover scaling in amorphous plasticity

Avalanche localization and crossover scaling in amorphous plasticity

Bloch-line dynamics within moving domain walls in 3D ferromagnets

Barkhausen Noise from Precessional Domain Wall Motion

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