Direct correlation of structural domain formation with the metal insulator transition in a VO₂ nanobeam

The electrical resistance of single VO₂ nanobeams was measured while simultaneously mapping the domain structure with Raman spectroscopy to investigate the relationship between structural domain formation and the metal-insulator transition. With increasing temperature, the nanobeams transformed from the insulating monoclinic M₁ phase to a mixture of the Mott-insulating M₂ and metallic rutile phases. Domain fractions were used to extract the temperature dependent resistivity of the M₂ phase, which showed an activated behavior consistent with the expected Mott-Hubbard gap. Metallic monoclinic phases were also produced by direct injection of charge into devices, decoupling the Mott metal-insulator transition from the monoclinic to rutile structural phase transition.