A MoON Race: Computational Design of a Heteroanionic Metal-Insulator Transition Compound Molybdenum Oxynitride

Using symmetry principles and electronic structure calculations we designed a novel metal-insulator transition (MIT) compound MoON [1]. The alpha and beta phase of this material were identified from a set of prototype AB₂ structures based upon energetics, band gap, and the c/a ratio. We show that the fac ordering of the polyhedra are important for charge localization, singlet formation, and opening of the band gap. Our density functional calculations show how changes in the electronic band gap are driven by structural distortions, including 1D chain canting and dimer formation. Last we draw parallels between MoON and the well-studied VO₂, demonstrating that properties such as the c/a lattice parameter ratio could be used for further design and identification of other rutile MIT materials.

Reference:
[1] N. Szymanski et al. Phys. Rev. Lett. 123, 236402 (2019)