Coupled Ferroelectricity and Optical Activity in Optically Active Ferroelectrics

Ferroelectricity was initially discovered in 1921 in Rochelle salt (potassium sodium tartrate tetrahydrate), a chiral compound containing a chiral unit. However, the inherent relationship between coupled ferroelectricity and optical activity in chiral ferroelectrics derived from achiral units, as well as in polar ferroelectrics, remains insufficiently explored. In this regard, we propose a fresh concept of optically active ferroelectrics, specifically those crystallizing in seven optically active point groups (1, 2, 4, 3, 6, m, mm2). Subsequently, we elucidate the mechanism of coupled ferroelectricity and optical activity, emphasizing the cooperative interplay of chirality and polarity flipping under the influence of an electric field. Finally, we expound on the applications of this principle for the in situ generation of chiral enantiomers and polar isomers, thereby providing valuable insights into the chiral/polar research community and advancing our comprehension of ferroelectricity.