Nonlinear Phenomena in Complex Systems, 2026, Vol.29, No.2, pp.151-161

NONLINEAR PHENOMENA IN COMPLEX SYSTEMS
An Interdisciplinary Journal

2026, Vol.29, No.2, pp.151-161

Effective Medium Modeling of Electrical Transport in CoFeB-SiO₂ and CoFeB--Al₂O₃ Nanogranular Films

A. V. Larkin and G. G. Voytko

Electrical conductivity in Co₄₁Fe₃₉B₂₀-SiO₂ and Co₄₁Fe₃₉B₂₀-Al₂O₃ nanogranular films deposited under different sputtering conditions has been analyzed within the framework of the effective medium approximation (EMA). Two-dimensional (2D), three-dimensional (3D), and generalized EMA models have been applied to describe the concentration dependence of the room-temperature conductivity and to investigate the influence of transport dimensionality on tunneling conductivity. Both the 2D and 3D EMA models reproduce the experimental conductivity curves reasonably well over the investigated concentration range; however, the extracted tunneling parameters depend systematically on the assumed dimensionality of the transport network. The generalized EMA model has revealed intermediate values of the effective transport exponent and dimensionality for several samples, indicating crossover behavior between idealized two-dimensional and three-dimensional transport regimes. The obtained results are consistent with the influence of film microstructure, finite-thickness effects, and intergranular tunneling barriers in conductivity formation in CoFeB-based granular nanocomposites.

Key words: effective medium approximation, electrical conductivity, nanocomposites, percolation, tunneling conductivity

DOI: https://doi.org/10.5281/zenodo.21105134

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