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Fractal Nature of Metallic and Insulating Domain Configurations in a VO<inf>2</inf> Thin Film Revealed by Kelvin Probe Force Microscopy

초록/요약

We investigated the surface work function (W<inf>S</inf>) and its spatial distribution for epitaxial VO<inf>2</inf>/TiO<inf>2</inf> thin films using Kelvin probe force microscopy (KPFM). Nearly grain-boundary-free samples allowed observation of metallic and insulating domains with distinct W<inf>S</inf> values, throughout the metal-insulator transition. The metallic fraction, estimated from W<inf>S</inf> maps, describes the evolution of the resistance based on a two-dimensional percolation model. The KPFM measurements also revealed the fractal nature of the domain configuration. © 2015, Nature Publishing Group. All rights reserved.

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