O

The magnetization of a molecule-based multiferroic, (NH₄)₂FeCl₅H₂O and its deuterated analog, was measured using pulsed magnetic fields of up to 60 T and temperatures down to 0.6 K, to reveal the magnetic field-temperature phase diagram. Density functional theory and numerical simulations of the exchange interactions demonstrates the origin of non-collinearity and multiferrocity within the system. The phase diagram is different to other multiferroic materials with a cascade of transitions up to and including the 31 T transition to the fully polarized state. Together, this opens the door to further exploration of the high field phase using powered and pulsed magnets.