Quantum ferroelectricity in SrTiO3 induced by oxygen isotope exchange

Oxygen isotope exchange results in a transition of SrTiO3 from quantum paraelectric to quantum ferroelectric. In the vicinity of the composition for the quantum limit, partially isotope-exchanged SrTiO3 shows a high dielectric constant ∼172 000, whereas unexchanged or fully exchanged SrTiO3 shows lower values. The composition dependence of partially oxygen-exchanged SrTiO3 can be explained by the quantum mechanical “vector model” proposed by Schneider et al. [Phys. Rev. B 13, 1123 (1976)].