Statistical and Multifractal Properties of Barkhausen Jumps in Exchange-Coupled Antiferromagnetic/Ferromagnetic Bilayers

Abstract

Statistical and multifractal properties of Barkhausen jumps in exchange-coupled ferromagnet/antiferromagnet bilayers are studied on Co/IrMn and NiFe/NiO heterostructures using a magneto-optical indicator film technique. The statistical analysis proves a nonstochastic character of magnetization jumps. In particular, power-law behavior is observed for Co/IrMn samples. Furthermore, the statistics depends on the ferromagnet layer thickness and antiferromagnet layer material structure. The average jump size displays an asymmetry between the forward and backward branches of the hysteresis loop, particularly pronounced for the structure with a thin Co layer. In spite of the observation of such an asymmetry in the activity of the domain nucleation and pinning centers, the statistical distributions of jumps do not show any significant differences for two branches of the hysteresis loop. The conclusion on a nonrandom character of the magnetization process is supported by the multifractal analysis which reveals the presence of correlations in the time arrangement of the Barkhausen jumps.

Magnetisation Processes in Geometrically Frustrated Spin Networks with Self-Assembled Cliques

“…These include the analysis of the magnetisation processes when the same building simplexes are self-assembled with a nonzero chemical affinity ν = 0, resulting in different structure of simplicial complexes [3,24], and the multifractal analysis of the magnetisation fluctuations [46,54] that occur in the passages between consecutive plateaus. Further studies are also necessary to investigate the role of higher-order connectivity of these assemblies when the interactions J ij ∈ [−J, J] assume random and non-integer values, in analogy to Ising spin-glasses, which are studied on regular lattices [55] and in antiferromagnetic/ferromagnetic bilayers [56]. Another question regards the changes in geometric frustration effects by including the three spin interactions or Heisenberg spins in the Hamiltonian.…”

Surface characterization of NiO thin films deposited by RF‐magnetron sputtering at different thickness: Statistical and multifractal approach

“…Therefore, researchers have been interested in studying the mechanical, electrical, optical, and morphological properties of thin films (Abdolghaderi et al, 2016; Astinchap et al, 2017; Usmani et al, 2017; Yildirim et al, 2017). Among the various properties of thin films, surface morphology is of particular importance because of its great effect on other properties (Elenkova et al, 2015; Shashkov et al, 2014). Surface properties are investigated using various instruments such as atomic force microscope (AFM), scanning electron microscope (SEM), and scanning tunneling microscope (STM) (Leach, 2013).…”

“…particular importance because of its great effect on other properties (Elenkova et al, 2015;Shashkov et al, 2014). Surface properties are investigated using various instruments such as atomic force microscope (AFM), scanning electron microscope (SEM), and scanning tunneling microscope (STM) (Leach, 2013).…”