Interface-induced collective phase transition in VO2-based bilayers studied by layer selective spectroscopy

Abstract

We investigated the origin of collective electronic phase transitions induced at the heterointerface between monoclinic insulating VO2 and rutile metallic electron-doped VO2 layers using in situ soft x-ray photoemission spectroscopy (PES) and x-ray absorption spectroscopy (XAS) on nanoscale VO2/V0.99W0.01O2 (001)R bilayers. Thanks to the surface sensitivity of PES and XAS, we determined the changes in the electronic structure and V-V dimerization in each constituent layer separately. The layer selective observation of the electronic and crystal structures in the upper VO2 layer of the bilayer indicates that the monoclinic insulating phase VO2 layer undergoes a transition to the rutile metallic phase by forming the heterointerface. Detailed temperature-dependent measurements reveal that the rutile metallic phase VO2 undergoes a transition to the monoclinic insulating phase with a decrease in temperature, as in the case of a VO2 single-layer film. Furthermore, during the temperature-induced phase transition in the VO2 layer, the spectra are well described by an in-plane phase separation of the rutile metallic and monoclinic insulating phases. These results suggest that the interface-induced transition from the monoclinic insulating to the rutile metallic phase in the VO2 layer of bilayers occurs as a collective phase transition derived from the static energy balance between the interfacial energy and the bulk free energies of the constituent layers.

Accepted by Scientific Reports on 2025-09-16. This is the author accepted manuscript (postprint). 34 pages (incl. 12-page Supplement); 4 figures in the main text and 7 in the Supplement. Corresponding author: Daisuke Shiga

References in corpus (17)

• Mott transition in VO2 revealed by infrared spectroscopy and nano-imaging
• Orbital-assisted metal-insulator transition in VO${}_2$
• Tunable polaronic conduction in anatase TiO2
• Direct Observation of Decoupled Structural and Electronic Transitions and an Ambient Pressure Monoclinic-Like Metallic Phase of VO${}_2$
• Nanoscale imaging of the electronic and structural transitions in vanadium dioxide
• Photoemission study of the metal-insulator transition in VO_2/TiO_2(001) : Evidence for strong electron-electron and electron-phonon interaction
• Effective band-structure in the insulating phase versus strong dynamical correlations in metallic VO2
• Correlation-driven insulator-metal transition in near-ideal vanadium dioxide films
• Unraveling the Mott-Peierls intrigue in Vanadium dioxide
• Epitaxial Growth of VO${}_2$ by Periodic Annealing
• Engineering two-dimensional electron gases at the (001) and (101) surfaces of TiO2 anatase using light
• Role of the V-V dimerization in insulator-metal transition and optical transmittance of pure and doped VO2 thin films
• Thickness dependence of electronic and crystal structures in VO${}_2$ ultrathin films: suppression of the collaborative Mott-Peierls transition
• Imaging the itinerant-to-localized transmutation of electrons across the metal-to-insulator transition in V${}_2$O${}_3$
• Emergence of metallic monoclinic states of VO${}_2$ films induced by K deposition
• Electronic phase diagram of Cr-doped VO2 epitaxial films studied by in situ photoemission spectroscopy
• Bilayer Vanadium Dioxide Thin Film with Elevated Transition Temperatures and High Resistance Switching