Playing with universality classes of Barkhausen avalanches

Abstract

Many systems crackle, from earthquakes and financial markets to Barkhausen effect in ferromagnetic materials. Despite the diversity in essence, the noise emitted in these dynamical systems consists of avalanche-like events with broad range of sizes and durations, characterized by power-law avalanche distributions and typical average avalanche shape that are fingerprints describing the universality class of the underlying avalanche dynamics. Here we focus on the crackling noise in ferromagnets and scrutinize the traditional statistics of Barkhausen avalanches in polycrystalline and amorphous ferromagnetic films having different thicknesses. We show how scaling exponents and average shape of the avalanches evolve with the structural character of the materials and film thickness. We find quantitative agreement between experiment and theoretical predictions of models for the magnetic domain wall dynamics, and then elucidate the universality classes of Barkhausen avalanches in ferromagnetic films. Thereby, we observe for the first time the dimensional crossover in the domain wall dynamics and the outcomes of the interplay between system dimensionality and range of interactions governing the domain wall dynamics on Barkhausen avalanches.

A Review of the Serrated-Flow Phenomenon and Its Role in the Deformation Behavior of High-Entropy Alloys

“…The figure displays the two main types of serrations: large primary serrations and small, interspersed secondary serrations. Serrations have also been observed in different phenomena, such as the Barkhausen noise in magnetic materials [8,[71][72][73][74] (see Figure 5), crackling noise during earthquakes [75][76][77][78], discrete strain bursts in nanocrystals [76], various economic indices [79][80][81][82][83], and neuronal avalanches that occur during the operation of the brain's network (see Figure 6) [84][85][86][87][88][89][90][91][92]. Endurance limits of the Al0.5CoCrCuFeNi HEA as a function of the ultimate tensile strength, compared with other structural materials and bulk metallic glasses (BMGs) (reproduced from Reference [68] with permission).…”

Waiting-time statistics in magnetic systems

“…For crackling noise in general, looking primarily at the temporal avalanche statistics, distribution of avalanche durations discloses a power-law scaling behavior, characterized by a scaling exponent that is independent of the threshold level for a reasonable range of values, as long as it is not too small or too large 6,9 . This is especially true for the Barkhausen avalanches in magnetic systems, for both bulk samples and thin films.…”

“…Or, on a macro-scale, the Earth's surface also responds with violent and intermittent earthquakes as the tectonic plates rub past one another 3 . Further, remarkably, crackling has been yet detected in the avalanche behavior of for instance micro-fracturing phenomena 4 , in the dynamics of superconducting vortices 5 , in the Barkhausen effect in ferromagnetic materials [6][7][8][9] , and even in the financial markets 10 . Despite crackling is found in fundamentally different systems, such systems often share general features.…”

“…These are the cases of for instance the distributions of avalanche sizes and avalanche durations, the average avalanche size as a function of its duration, the power spectrum, and the average temporal avalanche shape. Focusing just on the temporal avalanche statistics, it is well known that the distribution of avalanche durations follows a cutoff-limited power-law scaling behavior, which is associated to a scaling exponent 9 . This exponent is in general independent of the threshold level, thus reflecting general features of the underlying system dynamics and being a signature of an universality class.…”

Forecasting unprecedented ecological fluctuations

“…Avalanches are a specific type of discrete, impulsive fluctuation characterized by heavy-tailed power law distributions (or scaling laws) in size and a self-similarity between events of divergent scales that can arise from various microscopic generative processes [17,18]. These dynamics occur in many systems including earthquakes, magnet polarization, and neuronal firings [17][18][19]. Despite the diversity of systems that produce avalanches, the resulting dynamic scaling laws often fall into a limited set of so-called "universality classes" that are insensitive to the system specific details [17,20].…”