Electronic phase separation and emergence of a nondimerized insulating phase in VO2 (110)R ultrathin films
Abstract
Using in situ photoemission spectroscopy and x-ray absorption spectroscopy, we investigated the thickness dependence of the electronic structure and V-V dimerization in VO2/TiO2 (110) ultrathin films, in which the one-dimensional V-V chains along the cR axis lie in the film plane. In VO2 (110)R films, the reduction in dimensionality along the surface-normal direction is not expected to impose a geometric constraint on V-V dimerization, unlike in VO2 (001)R films. Nevertheless, the characteristic spectral changes associated with the temperature-driven metal-insulator transition observed in thick films persist down to 1.5 nm, whereas at 1 nm an insulating electronic phase is observed without V-V dimerization. This behavior is highly similar to that reported for VO2 (001)R, suggesting that the enhancement of Mott instability resulting from reduced dimensionality is a common and essential driving force for the emergence of the nondimerized insulating phase in VO2 ultrathin films. Meanwhile, unlike in VO2 (001)R, the nondimerized insulating phase in VO2 (110)R coexists with the phase exhibiting the temperature-driven metal-insulator transition. Its fraction increases exponentially with decreasing thickness and becomes dominant at 1 nm. The corresponding effective critical thickness is estimated to be 2.2 nm. These results imply that the geometric orientation of the V-V chains dictates the spatial evolution of electronic phase separation via strain-mediated phase competition.
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BibTeX
@misc{inoue2026electronic,
title = {{Electronic phase separation and emergence of a nondimerized insulating phase in VO$_2$ $(110)_\mathitR$ ultrathin films}},
author = {S. Inoue and D. Shiga and R. Hayasaka and K. Ozawa and A. F. Santander-Syro and H. Kumigashira},
howpublished = {arXiv},
year = {2026},
month = aug,
doi = {10.48550/arxiv.2608.29116},
eprint = {2608.29116},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.29116},
}
RIS
TY - UNPB
TI - Electronic phase separation and emergence of a nondimerized insulating phase in VO_2 (110)_R ultrathin films
AU - S. Inoue
AU - D. Shiga
AU - R. Hayasaka
AU - K. Ozawa
AU - A. F. Santander-Syro
AU - H. Kumigashira
PY - 2026
DA - 2026/08/29
PB - arXiv
DO - 10.48550/arxiv.2608.29116
UR - https://arxiv.org/abs/2608.29116
AB - Using in situ photoemission spectroscopy and x-ray absorption spectroscopy, we investigated the thickness dependence of the electronic structure and V-V dimerization in VO_2/TiO_2 (110) ultrathin films, in which the one-dimensional V-V chains along the c_R axis lie in the film plane. In VO_2 (110)_R films, the reduction in dimensionality along the surface-normal direction is not expected to impose a geometric constraint on V-V dimerization, unlike in VO_2 (001)_R films. Nevertheless, the characteristic spectral changes associated with the temperature-driven metal-insulator transition observed in thick films persist down to 1.5 nm, whereas at 1 nm an insulating electronic phase is observed without V-V dimerization. This behavior is highly similar to that reported for VO_2 (001)_R, suggesting that the enhancement of Mott instability resulting from reduced dimensionality is a common and essential driving force for the emergence of the nondimerized insulating phase in VO_2 ultrathin films. Meanwhile, unlike in VO_2 (001)_R, the nondimerized insulating phase in VO_2 (110)_R coexists with the phase exhibiting the temperature-driven metal-insulator transition. Its fraction increases exponentially with decreasing thickness and becomes dominant at 1 nm. The corresponding effective critical thickness is estimated to be 2.2 nm. These results imply that the geometric orientation of the V-V chains dictates the spatial evolution of electronic phase separation via strain-mediated phase competition.
ER -