Depolarizing-Field Effects in Epitaxial Capacitor Heterostructures.

We identify a transient enhancement of the depolarizing field, leading to an unexpected quench of net polarization, during the growth of a prototypical metal-ferroelectric-metal epitaxial system made of BaTiO3 and SrRuO3. Reduced conductivity and, hence, charge screening efficiency in the early growth stage of the SrRuO3 top electrode promotes a breakdown of ferroelectric BaTiO3 into domains. We demonstrate how a thermal annealing procedure can recover the single-domain state. By tracking the polarization state in situ, using optical second harmonic generation, we bring new understanding to interface-related electrostatic effects in ferroelectric capacitors.