paper

Thickness dependence of electronic and crystal structures in VO $_{2}$ ultrathin films: suppression of the collaborative Mott-Peierls transition

arXiv:2005.00304 · doi:10.1103/PhysRevB.102.115114

Abstract

Through $in s i t u$ photoemission spectroscopy, we investigated the change in the electronic and crystal structures of dimensionality-controlled VO $_{2}$ films coherently grown on TiO $_{2}$ (001) substrates. In the nanostructured films, the balance between the instabilities of a bandlike Peierls transition and a Mott transition is controlled as a function of thickness. The characteristic spectral change associated with temperature-driven metal-insulator transition in VO $_{2}$ thick films holds down to 1.5 nm (roughly corresponding to five V atoms along the [001] direction), whereas VO $_{2}$ films of less than 1.0 nm exhibit insulating nature without V-V dimerization. These results suggest that the delicate balance between a Mott instability and a bandlike Peierls instability is modulated at a scale of a few nanometers by the dimensional crossover effects and confinement effects, which consequently induce the complicated electronic phase diagram of ultrathin VO $_{2}$ films.

30 pages, 4 main figures, 4 supplementary figures

Thickness dependence of electronic and crystal structures in VO2​ ultrathin films: suppression of the collaborative Mott-Peierls transition

Abstract

Thickness dependence of electronic and crystal structures in VO $_{2}$ ultrathin films: suppression of the collaborative Mott-Peierls transition