Equivalent-circuit interpretation of the dielectric dispersion in ferroelectric superlattice capacitor

We present an alternative explanation to the dielectric dispersion at low frequency in ferroelectric superlattice capacitors. The dispersions were recently observed and attributed to the Maxwell-Wagner effects in O'Neil et al. [Appl. Phys. Lett., 77, (2000) 1520]. We alternatively explain the observations based on an equivalent circuit. For small stack periodicities that are less than a few angstroms, the model reaches similar conclusions that the Maxwell-Wagner effects contribute to the dielectric loss at low frequencies. For larger stack periodicities, the model interprets correctly the observations in O'Neil et al. Finally, the model appears useful for understanding dielectric responses in relaxor ferroelectrics, and thus suggests that stacking various ferroelectric thin films may produce relaxor responses. (C) 2001 Elsevier Science B.V. All rights reserved.