title: Quantitative mapping of phase coexistence in Mott-Peierls insulator during electronic and thermally driven phase transition.
abstract: Quantitative impedance mapping of the spatially inhomogeneous insulator-to-metal transition (IMT) in vanadium dioxide (VO2) is performed with a lateral resolution of 50 nm through near-field scanning microwave microscopy (SMM) at 16 GHz. SMM is used to measure spatially resolved electronic properties of the phase coexistence in an unstrained VO2 film during the electrically as well as thermally induced IMT. A quantitative impedance map of both the electrically driven filamentary conduction and the thermally induced bulk transition is established. This was modeled as a 2-D heterogeneous resistive network where the distribution function of the IMT temperature across the sample is captured. Applying the resistive network model for the electrically induced IMT case, we reproduce the filamentary nature of electronically induced IMT, which elucidates a cascading avalanche effect triggered by the local electric field across nanoscale insulating and metallic domains.
authors: Electrical Engineering Department, The Pennsylvania State University , University Park, Pennsylvania 16802, United States.
authors: Himanshu
authors: H
authors: Madan
authors: Matthew
authors: M
authors: Jerry
authors: Alexej
authors: A
authors: Pogrebnyakov
authors: Theresa
authors: T
authors: Mayer
authors: Suman
authors: S
authors: Datta
keywords: impedance mapping; insulator-to-metal transition; phase coexistence; phase transition; scanning microwave microscopy; vanadium dioxide