The role of π-blocking hydride ligands in a pressure-induced insulator-to-metal phase transition in SrVO<sub>2</sub>H.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 29089516.
- Also identified by DOI 10.1038/s41467-017-01301-0 and PMC identifier 5663929.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Transition-metal oxyhydrides are of considerable current interest due to the unique features of the hydride anion, most notably the absence of valence p orbitals. This feature distinguishes hydrides from all other anions, and gives rise to unprecedented properties in this new class of materials. Here we show via a high-pressure study of anion-ordered strontium vanadium oxyhydride SrVO<sub>2</sub>H that H<sup>-</sup> is extraordinarily compressible, and that pressure drives a transition from a Mott insulator to a metal at ~ 50 GPa. Density functional theory suggests that the band gap in the insulating state is reduced by pressure as a result of increased dispersion in the ab-plane due to enhanced V<sub>dπ</sub>-O<sub>pπ</sub>-V<sub>dπ</sub> overlap. Remarkably, dispersion along c is limited by the orthogonal V<sub>dπ</sub>-H<sub>1s</sub>-V<sub>dπ</sub> arrangement despite the greater c-axis compressibility, suggesting that the hydride anions act as π-blockers. The wider family of oxyhydrides may therefore give access to dimensionally reduced structures with novel electronic properties.