Gate-Tunable Correlated Electronic State in Atomically Thin Single-Crystal VO_2-δ.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Synthesizing high-quality two-dimensional (2D) correlated oxides, especially nonlayered systems, is challenging due to structural instability and sensitivity to stoichiometry.
• Atomic-scale synthesis of such materials is crucial for exploring novel quantum phenomena and developing advanced electronic devices.

Purpose of the Study:

• To report the successful chemical vapor deposition (CVD) growth of atomically thin, single-crystalline bronze-phase vanadium dioxide (2D VO2-δ).
• To investigate the potential of this 2D material platform for exploring correlation-driven physics and quantum phenomena.
• To demonstrate the creation of a hole-doped correlated metallic state via electrostatic gating.

Main Methods:

• Utilized a hydrogen-confined, self-terminating chemical vapor deposition (CVD) process for controlled synthesis.
• Achieved monolayer-level thickness precision and large lateral crystal sizes (up to hundreds of micrometers).
• Employed electrostatic ionic gating to induce and study electronic phase transitions.

Main Results:

• Successfully grew high-quality, single-crystalline 2D VO2-δ with precise thickness control.
• Induced a hole-doped correlated metallic state through ionic gating, a state not observed in bulk VO2.
• Observed transport signatures consistent with strong electron correlations in the 2D material.

Conclusions:

• Demonstrated the viability of 2D transition metal oxides (TMOs) as a platform for studying high-temperature correlated quantum phenomena.
• Highlighted the potential of these 2D TMOs for developing novel quantum electronic devices operating at room temperature.
• The hydrogen-confined CVD method offers a pathway for scalable synthesis of advanced 2D oxide materials.