The transverse magnetization components in the ground state of invar γ-Ni 1− cFe c alloys

Abstract

To separate magnetic and nuclear scattering and to obtain the quantitative information concerning the transverse components of magnetization in iron-nickel invar alloys we have undertaken a study of two alloys, Fe67Ni33 and 50Fe50Ni, with neutron polarization analysis at 40 and 300 K. The angular dependence of spin-flip and non-spin-flip scattering was measured on the diffractometer D5 of the ILL High Flux reactor. The main difference which is observed between invar and noninvar alloys concerns the spin-flip scattering, which occurs due to existence of an average transverse component μ ⊥ = 0.65 μ B . This value is well below than μ ⊥ = 1.15 μ B , calculated from the model where only HS state for iron atoms takes place ( μ Fe=2.8 μ B ). Thus, the LS iron state should be present inside of magnetic inhomogeneities with R ≅ 10–15 A ̊ .