Ferroelectric materials are characterized by a spontaneous polar distortion. The behavior of such distortions in the presence of free charge is the key to the physics of metallized ferroelectrics in particular, and of structurally-polar metals more generally. Using first-principles simulations, here we show that a polar distortion resists metallization and the attendant suppression of long-range dipolar interactions in the vast majority of a sample of 11 representative ferroelectrics. We identify a meta-screening effect, occurring in the doped compounds as a consequence of the charge rearrangements associated to electrostatic screening, as the main factor determining the survival of a non-centrosymmetric phase. Our findings advance greatly our understanding of the essentials of structurally-polar metals, and offer guidelines on the behavior of ferroelectrics upon field-effect charge injection or proximity to conductive device elements.
@article{arxiv.1802.07464,
title = {Meta-screening and permanence of polar distortion in metallized ferroelectrics},
author = {Hong Jian Zhao and Alessio Filippetti and Carlos Escorihuela-Sayalero and Pietro Delugas and Enric Canadell and Laurent Bellaiche and Vincenzo Fiorentini and Jorge Iniguez},
journal= {arXiv preprint arXiv:1802.07464},
year = {2018}
}