Second harmonic generation from ternary metal Prussian blue analog films in paramagnetic and ferromagnetic regions

Second harmonic generation (SHG) was observed from electrochemically synthesized magnetic thin films of ternary metal Prussian blue analogs (FeIIxCrII1−x)1.5[Cr(CN)6]·7.5H2O, but not from powdered samples. Makerʹs fringe pattern of the SH signal at room temperature showed that the electric polarization was oriented perpendicular to the film plane. The origin of the observed SHG was ascribed to the out-of-plane orientation of the electric-dipole moment produced by a distorted structure. Below the magnetic ordering temperature, the SH intensity increased with increasing magnetization; this indicates a contribution of the magnetic ordering to the non-linear optical susceptibility.