Enhancement of dielectric and ferroelectric properties of PbZrO ₃/PbTiO ₃ artificial superlattices

PbZrO ₃ (PZO)/PbTiO ₃ (PTO) artificial superlattices have been grown on La _0.5Sr _0.5CoO ₃ (LSCO) (100)/MgO (100) substrate by pulsed laser deposition with various stacking periods from 1 to 100 unit cells. The PZO/PTO artificial lattice exhibited a diffraction pattern characteristic of a superlattice structure, i.e., a main diffraction peak with satellite peaks. The electrical properties of the superlattices were investigated as a function of the stacking period. The dielectric constant and remnant polarization improved on decreasing the stacking periodicity. The dielectric constant of the superlattice reached 800 at a stacking period of lunit cell/lunit cell (PZO ₁/PTO ₁), which is larger than that of the single PZT solid-solution film. Moreover, the remnant polarization reached a maximum, 2Pr = 38.7 μC/cm ², at a 2-unit-cell stacking period. Progressive enhancement of dielectric constant and remnant polarization in artificial PZO/PTO superlattice was accompanied by expansion of the (100)-plane spacing on decreasing the stacking periodicity. These results suggest that the lattice strain developed in the PZO/PTO superlattice may have influence on dielectric constant and ferroelectric behavior.