Magnetically induced electric polarization in Ba3Fe2O5Cl2 with tunable direction in three dimensions

The correlation between magnetism and electric polarization in a chiral insulating magnet $\mathrm{B}{\mathrm{a}}_{3}\mathrm{F}{\mathrm{e}}_{2}{\mathrm{O}}_{5}\mathrm{C}{\mathrm{l}}_{2}$ has been investigated. The temperature dependence of magnetic susceptibility shows an anomaly at 564 K, suggesting the onset of antiferromagnetic order of $\mathrm{F}{\mathrm{e}}^{3+}$ moments. Electric polarization appears in a magnetic field below ${T}_{\mathrm{N}}$ due to the spin-direction-dependent metal-ligand hybridization. The direction of the electric polarization can be controlled in three-dimensional space by changing the direction of an external magnetic field. This compound also shows an antiferromagnetic-to-weak-ferromagnetic transition accompanied by a structural phase transition at 140 K.