Suppression of Metal-Insulator Transition in VO 2 by Electric Field–Induced Oxygen Vacancy Formation

Electrolyte gating with ionic liquids is a powerful tool for inducing novel conducting phases in correlated insulators. An archetypal correlated material is vanadium dioxide (VO(2)), which is insulating only at temperatures below a characteristic phase transition temperature. We show that electrolyte gating of epitaxial thin films of VO(2) suppresses the metal-to-insulator transition and stabilizes the metallic phase to temperatures below 5 kelvin, even after the ionic liquid is completely removed. We found that electrolyte gating of VO(2) leads not to electrostatically induced carriers but instead to the electric field-induced creation of oxygen vacancies, with consequent migration of oxygen from the oxide…