Magnetization and nuclear magnetic resonance (spin‐echo) studies on an amorphous Co‐Fe‐Mn‐B‐Si alloy

Magnetization and nuclear magnetic resonance spin‐echo studies were carried out on an amorphous Co‐Fe‐Mn‐B‐Si alloy ribbon. The high‐field susceptibility is negligible and saturation is attained at H ∼1.6 MA/m. This would indicate that the alloy is a strong ferromagnet. At 4.2 K, the magnetic moment of the alloy corresponds to 1.13 μ B per atom. From the usual values of Co and Fe moments, and based on the charge transfer model, the Mn moment is estimated to be 3.7 μ B . Nuclear magnetic resonance studies also give a hyperfine field for Mn corresponding to a moment of about 3.5μ B , in agreement with the magnetization values. Such a moment for Mn is indeed high and is reported for the first time in amorphous alloys. The effects of annealing and crystallization on the nuclear magnetic resonance spectra are also reported. For instance, the crystalline phase Co3B contains Mn as an impurity, a fact which is indicated by the still high value of the Mn moment. Finally, the Co‐Mn coupling is shown to be ferromagnetic in both the amorphous and crystalline states.