Range of Magnetic Interactions in Some Anhydrous Sulphates of the 3d Transition Metals

Several three‐parameter analyses are performed on β‐FeSO₄, α‐FeSO₄, α‐NiSO₄, and α‐MnSOsb₄ by selecting the exchange interactions among the set (J₁, J₂, J₃, J₄). These compounds disclose different spin configurations. As input data the experimental values for T_N,χ(T_N) are used and the second moments of the energy distributions of neutrons scattered by polycrystalline samples in their paramagnetic state. It is possible to determine the significant parameters. It is concluded that, in this series of compounds, the interactions extend up to the fourth neighbours, although the relative importance of the various parameters depends strongly on the ordering type.