Barkhausen effect in a garnet film studied by ballistic hall micromagnetometry

The movement of a micrometer-size section of a single domain wall in a uniaxial garnet film was studied using a ballistic Hall micromagnetometer at 77 K and 4.2 K. The wall propagated in characteristic Barkhausen jumps, with the jump size distribution following the power-law relation, P(S) ∝ S−τ. The scaling exponent, τ, was measured as 1.14 ± 0.05 at both temperatures. This is the first measurement of this exponent using such a device, and the first for a single wall in a two-dimensional sample with a low concentration of pinning centres, in which the magnetization of the sample is perpendicular to the surface.