Structure-independent universality of Barkhausen criticality in iron nitride thin films

摘要

Discrete and jerky jumps during the process of magnetization reversal in ferromagnetic systems cause Barkhausen intermittency. We have investigated critical scaling behavior of the Barkhausen avalanche of 2-dimensional γ-Fe_4N thin films using a magneto-optic microscope magnetometer (MOMM) capable of time-resolved magnetic domain images. A statistical analysis of the fluctuating size of Barkhausen jumps from numerous repetitive experiments shows a power-law scaling behavior in the ferromagnetic iron nitride system exhibiting a critical exponent value of τ=1.02 within the experimental error. The value of critical exponent is found to manifest universality irrespective of the degree of texture of the film induced by annealing temperature.