  We investigate the origin of the depolarization rates in ultrathin
adsorbate-stabilized ferroelectric wires. By applying density functional theory
calculations and analytic modeling, we demonstrate that the depolarization
results from the leakage of charges stored at the surface adsorbates, which
play an important role in the polarization stabilization. The depolarization
speed varies with thickness and temperature, following several complex trends.
A comprehensive physical model is presented, in which quantum tunneling,
Schottky emission and temperature dependent electron mobility are taken into
consideration. This model simulates experimental results, validating the
physical mechanism. We also expect that this improved tunneling-Schottky
emission model could be applied to predict the retention time of polarization
and the leakage current for various ferroelectric materials with different
thicknesses and temperatures.
