Electronic and Lattice Dynamical Properties of MgTa₂O₆

Materials exhibiting metal-insulator transitions (MIT) are proposed platforms for next-generation low-power electronics. In addition, most of these materials exhibit strong coupling between the electronic and lattice degrees-of-freedom, which makes them ideal systems to examine the interplay between lattice dynamics, electronic structure, and magnetic order. Well-studied rutile-structured MIT oxides, such as VO₂ and NbO₂, exhibit dimerized cations within the edge-connected octahedra along the c axis in the insulating state. Analogous compounds with the related trirutile superstructure, e.g., V₂WO₆ and CuSb₂O₆, exhibit a similar dimerization. Here we investigate the propensity for MIT in MgTa₂O₆, a d⁰ insulator, upon electron doping. Our calculations suggest that MgTa₂O₆ remains metallic for electron doping configurations within the d^0.25-d^0.5 range, whereas Ta-Ta dimerization occurs for higher electron concentations. Overall, these results indicate that trirutile oxides may be a promising materials class for which to functionalize MITs.