Assessing the K₂BO₃ family of materials as multiferroics

Abstract

We evaluate the potential of an overlooked family of materials to support both the magnetization and polarization required to be classified as multiferroics. This family of materials has a stoichiometry of A₂BX₃ and was uncovered in the Inorganic Crystal Structure Database (ICSD) while searching for structural platforms that could support low energy polarization switching. The examples here have the general chemical formula of K₂BO₃, where B is a magnetically active cation located within edge-sharing square pyramids that form a 1D chain. Density functional theory with Hubbard U corrections (DFT + U) are used to determine the potential energy landscape of K₂BO₃, which include investigating multiple magnetic and polarization orderings. We analyze the ground state and electronic structures and report on how the choice of Hubbard U will affect both, which is important when predicting functional properties of low-dimensional and potentially exfoliable systems. This family contains a ferromagnetic insulator, K₂VO₃, as well as antiferromagnetic (K₂NbO₃) and nonmagnetic (K₂MoO₃) insulators with antipolar ground state symmetries, and accessible polar metastable states, that we predict to be antiferroelectric. This preliminary assessment of the K₂BO₃ members of the A₂BX₃ family reveals a new class of materials, that with further optimization via compositional tuning, could be multiferroic.