Magnetism in FeCl₂ at high pressures

Anhydrous FeCl₂ has been studied by ⁵⁷Fe Mössbauer effect up to 61 GPa and at 5 < T < 300 K using diamond-anvil-cells. In the 3.5-31 GPa range an average hyperfine field of ∼1.2 T is observed, attributed to mutual cancellation of Fermi-contact and orbital terms. At P ≥ 34 GPa the orbital term is abruptly quenched resulting in enhanced hyperfine field. At P > 42 GPa the onset of a diamagnetic phase is observed, signifying a total collapse of magnetism at P > 61 GPa.