A new fundamental limit of ferroelectric devices and its domain dynamics in ultrathin ferroelectric BaTiO$_{3}$ films

Phenomena in ultrathin ferroelectric (FE) films, such as the critical thickness and the domain structures, have attracted much interest for a few years. We fabricated fully-strained SrRuO$_{3}$/BaTiO$_{3} $/SrRuO$_{3}$ capacitors, whose BaTiO$_{3}$ layer thicknesses were between 5 and 30 nm, using the laser molecular beam epitaxy. We found that rapid decay of net polarization occurs due to large depolarization field [1]. Using the Monte-Carlo simulations, this decay can be explained by the domain formation dynamics, governed by the domain nucleation process. We found a universal relation between the decay exponent and nucleation energy barrier, regardless of film thickness and temperature. This universal relation will provide a fundamental thickness limit for practical FE devices, set by net polarization decay. [1] D. J. Kim et al. Phys. Rev. Lett, in press.