Composition dependence of field induced anisotropy in ferromagnetic „Co,Fe...89Zr7B4 and „Co,Fe...88Zr7B4Cu1 amorphous and nanocrystalline ribbons

The composition dependence of field induced anisotropy KU of field annealed soft ferromagnetic Co1−xFex 89Zr7B4 and Co1−xFex 88Zr7B4Cu1 amorphous and amorphous/nanocrystalline “nanocomposite” melt spun ribbons is investigated. With the exception of the highest Co-containing alloys x 0.10 , the observations are discussed in terms of a superposition of directional pair ordering of Fe,Co atoms and an additional contribution presumably due to the presence of Zr and B in both the field crystallized and field annealed amorphous ribbons. The highest Co-containing alloys x 0.10 contain multiple nanocrystalline phases bcc, fcc, and hcp for which a peak in KU is observed KU 2000–2500 J /m3 . In this framework, asymmetry in the compositional dependence of KU resulting in larger values for Co-rich alloys relative to Fe-rich alloys for both the field crystallized and field annealed amorphous alloys is explained in terms of a strong dependence of the Curie temperature of the amorphous phase on the Co content. © 2008 American Institute of Physics. DOI: 10.1063/1.3021141