Slow relaxation of the polarization in pulsed laser ablated highly oriented ferroelectric thin films

The relaxation of the polarization (as determined by the pyroelectric effec t) of high quality laser ablated films of PbZr0.52Ti0.48O3 has been measure d after saturation with an applied electric field. The decay is observed to be quasilogrithmic over four decades in time. Analysis of measurements of the remanent polarization and the depolarization remanence are consistent w ith the depolarization field providing a polarization-state-dependent field of the correct direction to drive the decay. Also, the quasilogrithmic tim e dependence is consistent with a model for slow relaxation or creep with t he depolarization field the driving field for the decay. These observations along with our AFM measurements imply that for maximum polarization stabil ity a ferroelectric film should consist of decoupled grains. The optimum gr ain size should be the maximum grain size which does not support domain wal ls.