Octahedral Symmetry Modification Induced Orbital Occupancy Variation in VO₂

Area of Science:

• Materials Science
• Solid-State Physics
• Oxide Electronics

Background:

• Complex oxides possess tunable functional properties influenced by octahedral symmetry.
• Vanadium dioxide (VO2) exhibits a near-room-temperature insulator-metal transition (IMT) linked to structural changes.

Purpose of the Study:

• To elucidate the role of octahedral symmetry in VO2 on its insulator-metal transition (IMT) characteristics.
• To investigate how structural modifications impact the electronic properties and IMT behavior of VO2.

Main Methods:

• Experimental analysis of crystal and electronic structures.
• Computational modeling using density-functional-theory (DFT) calculations.
• Focus on monoclinic VO2 films with varying octahedral symmetry.

Main Results:

• High octahedral symmetry in VO2 films leads to an expanded apical V-O length, increasing conduction band bandwidth by reducing V 3d-O 2p hybridization.
• This structural change enhances interdimer hopping energy, consequently lowering the insulator-metal transition temperature.
• Despite increased electron correlation due to shorter V-V chains, octahedral symmetry effectively controls IMT characteristics by altering orbital occupancy.

Conclusions:

• Octahedral symmetry is a critical parameter for tuning the insulator-metal transition (IMT) in vanadium dioxide (VO2).
• Modulating octahedral symmetry offers a pathway to control the IMT temperature and electronic properties of VO2 films.