Surface and bulk magnetic properties of amorphous and nanocrystalline Ni-substituted FINEMET samples

The effect of partial substitution of Fe by Ni on the bulk and surface magnetic properties in as-quenched and nanocrystalline Fe_73.5?xNi_xCu₁Nb₃Si_13.5 (x = 0, 8, 10 and 20) alloys has been investigated. A study of the variation of the surface magnetic properties with oxidation in these alloys is also presented. The surface hysteresis loops were obtained by the transverse magneto-optical Kerr effect. The experimental results show that the as-quenched and annealed samples with lower surface coercive field values are those with lower Fe/Si ratio in the sample surfaces. No significant changes between the values of surface H_c for the oxidized and non-oxidized annealed samples with the same Ni content have been observed.