The Additional Magnetic Anisotropy Induced by Magnetic Anneal in Ferromagnetic Face-Centered Cubic Solid Solutions : Part. II. Crystal Orientation Dependence of the Induced Magnetic Anisotropy in Face-Centered Cubic Nickel-Cobalt and Nickel-Iron Alloys

The induced uniaxial ferromagnetic anisotropy as a function of the crystal orientation has been measured, using a torque magnetometer, with magnetically annealed (110) disc single crystals of 12 and 20 %Co-Ni and 17 and 46 %Fe-Ni alloys. It has been found that the crystal orientation dependence of the induced uniaxial ferromagnetic anisotropy energy, E_u, is expressed by the formula E_u=-K(Σ_iα_i^2β_i^2+kΣ_j>iα_iα_jβ_iβ_j), where K is a positive constant, k a numerical factor, and α_i\u27s and β_i\u27s (i=1, 2, 3) the direction cosines of magnetization vectors during the torque measurement and during magnetic annealing, respectively. The factor k is 2～3 except for Ni-Fe alloys nearby Ni_3Fe, being smaller than 4 as expected from the directional order theory for face-centered cubic alloys. This difference may partly be due to the fact that the contribution from the second neighbor atoms is neglected in the theory, and rather large values of k for Ni-Fe alloys nearby Ni_3Fe may be due to the presence of superlattice