Near-surface magnetic properties of Co-based amorphous ribbons

The near-surface magnetic properties of as-cast and annealed (for various times in open air at a temperature T=380°C) Co 66Fe 4B 15Si 15 amorphous ribbons were studied by using a magneto-optical magnetometer. The effect of etching of the annealed samples on their near-surface magnetic properties was investigated. The annealed samples exhibit the presence of a hard near-surface magnetic layer. The hysteresis loops of the etched ribbons change strongly. For etching times ( t etch) larger than 50 s, an influence of the ribbon core on the near-surface magnetic properties of the sample was observed. For t etch>120 s, the hysteresis loops and other magnetic properties of the etched and as-cast samples were practically identical.