Time-dependent polarization relaxation behaviors induced by a depolarization field $E_{ d}$ were investigated on high-quality ultrathin SrRuO$_{ 3}$/BaTiO$_{ 3}$/SrRuO$_{ 3}$ capacitors. The $E_d$ values were determined experimentally from an applied external field to stop the net polarization relaxation. These values agree with those from the electrostatic calculations, demonstrating that a large $E_{ d}$ inside the ultrathin ferroelectric layer could cause severe polarization relaxation. For numerous ferroelectric devices of capacitor configuration, this effect will set a stricter size limit than the critical thickness issue.
Categories: cond-mat.mtrl-sci