Dramatically enhanced polarization in (001), (101), and (111) BiFeO3 thin films due to epitiaxial-induced transitions

Dramatically enhanced polarization has been found for $\left(001\right)$ , $\left(101\right)$ , and $\left(111\right)$ films, relative to that of ${\mathrm{BiFeO}}_3$ crystals. The easy axis of spontaneous polarization lies close to $\left(111\right)$ , for the various oriented films. ${\mathrm{BiFeO}}_3$ films grown on $\left(111\right)$ have a rhombohedral structure, identical to that of single crystals; whereas films grown on $\left(101\right)$ or $\left(001\right)$ are monoclinically distorted from the rhombohedral structure, due to the epitaxial constraint.