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 M-1 phase to a mixture of the Mott-insulating M-2 and metallic rutile phases. Domain fractions were used to extract the temperature dependent resistivity of the M-2 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.