Abstract
The ferroelectric polarization loop of an epitaxial BiFeO3 film on a piezoelectric substrate has been measured as a function of the continuously and reversibly varied biaxial strain of e = 0.36 – 0.51 %. Over this range, the ferroelectric coercive field (Ec) at 80 K increases reversibly by 36 % with the increasing tensile strain. The strain dependence of the remanent polarization agrees with previous experimental results and simulations based on thermodynamic considerations. In contrast, such calculations predict dEc/de <0, contradicting our experiments. Thus, the strain dependence of kinetic barriers influencing the rates of domain wall nucleation and propagation – which are neglected in thermodynamic models – may dominate the observed positive dEc/de.
