Non-collinear ferrimagnetism in a Fe64Er19B17 metallic glass.

Polarized neutron beam measurements on a Fe(64)Er(19)B(17) metallic glass have shown directly that it has a non-collinear magnetic structure. It can be described using a model in which the magnetic moments on the iron atoms point in a random cone that is ferrimagnetically coupled to a random cone of erbium moments, in the manner suggested from bulk measurements. The spin-flip cross-sections were successfully calculated using an optimized choice of the values of the magnetic moments μ(Fe), μ(Er) and the random cone angles θ(Fe), θ(Er). The non-spin-flip cross-sections have an unusual variation with the scattering vector Q, which has not been observed before with transition metal-metalloid glasses. At 1.5 and 60 K the [Formula: see text] cross-section contains a pre-peak at a smaller value of Q (1.3 Å(-1)) than the pre-peaks which have been observed in the structure factors of some transition metal glasses. At 180 K the form of these cross-sections remains the same but the two channels have interchanged, so [Formula: see text] contains the pre-peak. This interchange shows that a complete inversion of the magnetic structure occurs between 60 and 180 K-presumably at the compensation temperature T(comp)≈120 K. Attempts to simulate these cross-sections using the methods applied to (Fe,Tb)B glasses were unsuccessful because none of the known partial structure factors contains a pre-peak which can imitate the observed one. The possible origins of the pre-peak are discussed.