Abstract
A parameterized effective Hamiltonian approach is used to investigate . We find that the experimentally observed anomalous dielectric response of this incipient ferroelectric is well reproduced by this approach, once quantum effects are accounted for. Quantum fluctuations suppress the paraelectric-to-ferroelectric phase transition; it is unnecessary to introduce defects to explain the dielectric behavior. The resulting quantum-induced local structure exhibits off-center atomic displacements that display longitudinal, needle-like correlations extending a few lattice constants.
- Received 22 December 2003
DOI:https://doi.org/10.1103/PhysRevB.70.054103
©2004 American Physical Society