Susceptibility of non-crystalline ferromagnetic FeF2

Abstract

In the temperature range 150 K > T > 25 K the magnetic susceptibility of non-crystalline FeF2 can be described by a Curie-Weiss law. A paramagnetic Curie temperature of θ = (22 ± 1) K and an effective moment of peff = (5.2 ± 0.1) μB are found. Temperature and field dependence of the magnetization between 15 K-20.5 K indicate superparamagnetic behaviour. At lower temperatures the magnetization shows hysteresis and a slightly time dependent remanence. The observation of moments which approach 4 μ B/Fe2+ implies that the ordered state is ferromagnetic