A grand challenge of contemporary condensed matter physics is the understanding of the emergence of metallic transport in correlated insulators or Mott insulators in which, for example, a temperature change or chemical doping induces anomalous conducting phases. Where charge, spin, orbital and phononic degrees of freedom result in competing interactions, exotic phases emerge including the pseudogap state in cuprates and manganites, high-temperature superconductivity, even phase separation in some manganites and cuprates. I will report on the electronic properties of a prototypical correlated insulator vanadium dioxide (VO2) in which the metallic state is induced by increasing temperature. The pioneering technique of 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 VO2. In combination with far-field infrared spectroscopy, the data reveal divergent optical mass in the metallic puddles which is evidence of a Mott transition.
(Everyone is welcome to attend)
Dr. Mumtaz Qazilbash is a candidate for the Experimental Condensed Matter Physics Position.