Mott transition in VO2 revealed by infrared spectroscopy and nano-imaging

Abstract

Electrons in correlated insulators are prevented from conducting by Coulomb repulsion between them. When an insulator-to-metal transition is induced in a correlated insulator by doping or heating, the resulting conducting state can be radically different from that characterized by free electrons in conventional metals. We report on the electronic properties of a prototypical correlated insulator vanadium dioxide (VO2) in which the metallic state can be induced by increasing temperature. Scanning near-field infrared microscopy allows us to directly image nano-scale metallic puddles that appear at the onset of the insulator-to-metal transition. In combination with far-field infrared spectroscopy, the data reveal the Mott transition with divergent quasiparticle mass in the metallic puddles. The experimental approach employed here sets the stage for investigations of charge dynamics on the nanoscale in other inhomogeneous correlated electron systems.

22 pages (including 3 figures)

References in corpus (3)

• Visualizing pair formation on the atomic scale in the high-Tc superconductor Bi2Sr2CaCu2O8+d
• Correlated metallic state of vanadium dioxide
• Surface versus bulk characterization of the electronic inhomogeneity in a VO_{2} film

Cited by in corpus (9)

• Electrodynamics of the vanadium oxides VO2 and V2O3
• Infrared spectroscopy and nano-imaging of the insulator-to-metal transition in vanadium dioxide
• Multiple Avalanches Across the Metal-Insulator Transition of Vanadium Oxide Nano-scaled Junctions
• Signature of persistent metallic domains in FORC measurements of the VO${}_2$ metal-insulator transition
• Optical properties of correlated materials -- Generalized Peierls approach and its application to VO2
• Electrostatic modification of infrared response in gated structures based on VO2
• Materials Design using Correlated Oxides: Optical Properties of Vanadium Dioxide
• Optical Properties of Correlated Materials -- or Why Intelligent Windows may look Dirty
• Electronic inhomogeneity in EuO: Possibility of magnetic polaron states