Abstract
Vanadium dioxide (VO2) is a material that undergoes an insulator–metal transition upon heating above 340 K. It remains debated as to whether this electronic transition is driven by a corresponding structural transition or by strong electron–electron correlations. Here, we use apertureless scattering near-field optical microscopy to compare nanoscale images of the transition in VO2 thin films acquired at both mid-infrared and terahertz frequencies, using a home-built terahertz near-field microscope. We observe a much more gradual transition when THz frequencies are utilized as a probe, in contrast to the assumptions of a classical first-order phase transition. We discuss these results in light of dynamical mean-field theory calculations of the dimer Hubbard model recently applied to VO2, which account for a continuous temperature dependence of the optical response of the VO2 in the insulating state.
Original language | English (US) |
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Article number | 3604 |
Journal | Nature communications |
Volume | 9 |
Issue number | 1 |
DOIs | |
State | Published - Dec 1 2018 |
Externally published | Yes |
Bibliographical note
Publisher Copyright:© 2018, The Author(s).