Correlation induced emergent charge order in metallic vanadium dioxide thin films*

Understanding the metal-insulator transition in vanadium dioxide is complicated by symmetry breaking structural transitions accompanying correlated electronic transitions. Resolving this problem though is at the heart of many scientific and technological advancements. To that end, we develop a cross-phase, symmetry-consistent approach to treat structural distortions and electronic correlations in epitaxial VO₂ films from first principles. By adopting a uniform Bravais symmetry across several epitaxial growth configurations, we demonstrate the exquisite sensitivity of correlation physics to apical bond lengths in the presence of lattice symmetry breaking, and discover emergent charge order preceding the dimerized insulating phase even in the metallic rutile phase. We discuss the deep physical implications for the phase diagram of VO₂, and argue for the unparalleled significance of correlation physics and sample quality in light of this result.