Assessing the K2BO3 family of materials as multiferroics

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 A2?BX3 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 K2?BO3, 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 K2?BO3, 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, K2?VO3, as well as antiferromagnetic (K2?NbO3) and nonmagnetic (K2?MoO3) insulators with antipolar ground state symmetries, and accessible polar metastable states, that we predict to be antiferroelectric. This preliminary assessment of the K2?BO3 members of the A2?BX3 family reveals a new class of materials, that with further optimization via compositional tuning, could be multiferroic.