Motivated by the recently discovered superconductivity in Sr-doped nickelate oxides NdNiO2, we predict a material BiNiO2 that provides an opportunity to study the intertwined ferroelectricity, metallicity, and magnetism in a crystal with very simple atomic structures. There is a ferroelectric structural transition from the nonpolar phase with the P4/mmm space group to the polar phase with the P4mm space group, which is driven by the lone pair on Bi. Calculations based on the Heyd-Scuseria-Ernzerhof hybrid density functional reveal that both the nonmagnetic and ferromagnetic states are metallic for nonpolar and polar phases, while the lowest energy ground-state for polar BiNiO2 is a Hubbard Mott insulator with the G-type antiferromagnetic spin configurations. As a ferroelectric material with an electric polarization of 0.49 C/m2, it may be possible to control the magnetic order in BiNiO2 by an applied electric field. The replacement of Nd by Bi serves as a connecting link between a high-temperature superconductor and a Mott multiferroic. Our work supports a route towards strongly correlated ferroelectrics.
@article{arxiv.2302.00172,
title = {From a superconductor NdNiO$_2$ to a Mott multiferroic BiNiO$_2$},
author = {Hu Zhang and RuiFeng Zhang and Lulu Zhao and Chendong Jin and Ruqian Lian and Peng-Lai Gong and RuiNing Wang and JiangLong Wang and Xing-Qiang Shi},
journal= {arXiv preprint arXiv:2302.00172},
year = {2024}
}