Probing intrinsic polarization properties in bismuth-layered ferroelectric films

The authors report on an approach to establish intrinsic polarization properties in bismuth-layered ferroelectric films by piezoelectric coefficient and soft-mode spectroscopy, as well as by a direct polarization-electric field hysteresis. In epitaxially grown (Bi4-x Ndx) Ti3 O12 (0≤x≤0.73) films, they show that these complementary characterizations can phenomenologically and thermodynamically represent the intrinsic polarization states in (Bi4-x Ndx) Ti3 O12 films, and the intrinsic Ps of 67 μC cm2 is estimated for pure Bi4 Ti3 O12, superior to 50 μC cm2 in bulk single crystal. Their results provide a pathway to draw full potential in ferroelectric thin films.