Mathematical Double‐Matrix Switchable Homochiral Ferroelectric

Source abstract

Abstract Homochiral ferroelectrics have attracted increasing attention in recent years because of their distinctive chiroptical effects in contrast to ordinary ferroelectrics. Moreover, they provide a great opportunity to show mathematically switchable matrix elements between nonzero and zero values in both second‐order nonlinear optical susceptibility χ (2) and piezoelectric d matrices to realize the dual on/off switching of second‐harmonic generation circular dichroism (SHG‐CD) and piezoelectric responses, which, however, has never been reported. Herein, for the first time, we reported homochiral metal halide ferroelectrics ( R ‐/ S ‐BTA) 2 CdBr 4 (BTA = 3‐bromo‐2‐hydroxypropyltrimethylammonium), which exhibits a 432 F 2 ferroelectric phase transition at 362 K, accompanied by the switchable matrix elements between nonzero (for point group 2) and zero (for point group 432) values in both χ (2) and d matrices. They show strong SHG‐CD effects with an anisotropy factor up to 1.28, far exceeding that of other chiral ferroelectrics. Notably, the 432 F 2 phase transition enables ( R ‐/ S ‐BTA) 2 CdBr 4 to show the unprecedented dual on/off switching of SHG‐CD and piezoelectric response between the SHG‐CD/piezoelectric active state in the ferroelectric phase and SHG‐CD/piezoelectric inactive state in the paraelectric phase. Our findings shed light on the exploration of mathematical double‐matrix switchable chiral ferroelectrics with SHG‐CD and piezoelectric response switching.