Ferroelectricity in SbSI

The photoconducting compound SbSI was found to be ferroelectric with a Curie point at 22\ifmmode^\circ\else\textdegree\fi{}C. It has a high spontaneous polarization of ${P}_{s}=25\ensuremath{\mu}\mathrm{C}/{\mathrm{cm}}^{2}$ and a small coercive field strength of ${E}_{c}=100$ V/cm at 0\ifmmode^\circ\else\textdegree\fi{}C. The dielectric constant at the Curie point reaches values as high as 50 000. The switching is relatively fast and depends on the applied field according to a power law. It appears that the unusually large field-induced shift in absorption edge in SbSI and its electromechanical behavior can be explained by the fact that the material becomes ferroelectric below room temperature.