title: Quantum fluctuations and the closing of the Coulomb gap in a correlated insulator.
abstract: The "switchable mirror" yttrium hydride is one of the few strongly correlated systems with a continuous Mott-Hubbard metal-insulator transition. We systematically map out the low temperature electrical transport from deep in the insulator to the quantum critical point using persistent photoconductivity as a drive parameter. Both activated hopping over a Coulomb gap and power-law quantum fluctuations must be included to describe the data. Collapse of the data onto a universal curve within a dynamical scaling framework (with corrections) requires znu=6.0+/-0.5, where nu and z are the static and dynamical critical exponents, respectively.
authors.affiliation: The James Franck Institute and Department of Physics, The University of Chicago, Chicago, IL 60637, USA.
authors.forename: A S
authors.initials: AS
authors.lastname: Roy
authors.forename: A F Th
authors.initials: AF
authors.lastname: Hoekstra
authors.forename: T F
authors.initials: TF
authors.lastname: Rosenbaum
authors.forename: R
authors.initials: R
authors.lastname: Griessen