Prediction of a native ferroelectric metal

Authors

A. Filippetti, V. Fiorentini, F. Ricci, P. Delugas, and J. Iniguez

Reference

Nature Communications, vol. 7, no. 11211, 2016

Description

Over 50 years ago, Anderson and Blount discussed symmetry-allowed polar distortions in metals, spawning the idea that a material might be simultaneously metallic and ferroelectric. While many studies have ever since considered such or similar situations, actual ferroelectricity—that is, the existence of a switchable intrinsic electric polarization—has not yet been attained in a metal, and is in fact generally deemed incompatible with the screening by mobile conduction charges. Here we refute this common wisdom and show, by means of first-principles simulations, that native metallicity and ferroelectricity coexist in the layered perovskite Bi₅Ti₅O₁₇. We show that, despite being a metal, Bi₅Ti₅O₁₇ can sustain a sizable potential drop along the polar direction, as needed to reverse its polarization by an external bias. We also reveal striking behaviours, as the self-screening mechanism at work in thin Bi₅Ti₅O₁₇ layers, emerging from the interplay between polar distortions and carriers in this compound.

Link

doi:10.1038/ncomms11211