Artificial ferroelectricity in perovskite superlattices

Abstract

Artificial superlattices of SrZrO3(SZO)∕SrTiO3(STO) were fabricated by molecular-beam epitaxy. Lattice parameters showed that the lattice distortion (c∕a ratio) attained a maximum value in the [(SZO)10∕(STO)10]4 superlattice. Dielectric relaxation was observed in the [(SZO)1∕(STO)1]40 and [(SZO)10∕(STO)10]4 superlattices in the low frequency domain. Dielectric permittivity of the SZO∕STO superlattices was over 10 000 at 110MHz. The SZO∕STO superlattices showed clear Q–V hysteresis curves, which indicated that ferroelectricity was induced artificially in the superlattices in spite of the paraelectric nature of SZO and STO. The origin of the ferroelectricity was related to the anisotropic lattice distortion in the superlattice structure.