title: Charge dynamics near the electron-correlation induced metal-insulator transition in pyrochlore-type molybdates.
abstract: The systematics of the bandwidth controlled metal-insulator transition (MIT) are investigated for R2Mo2O7 (R=Nd, Sm, Gd, Dy, and Ho) by measurements of dc and optical conductivity. The substantial role of electron correlation in driving the MIT is verified. With changing the R ionic radius (r) or equivalently the one-electron bandwidth, the T=0 K MIT occurs at rc approximately r(R=Gd). The T=0 K gap continuously vanishes as Delta proportional, variant(rc-r), while at the metallic side the decrease of Drude weight is followed towards rc. A high-temperature incoherent state is approached through crossover regions both from the metallic and the insulating state.
authors.affiliation: Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan.
authors.forename: I
authors.initials: I
authors.lastname: Kézsmárki
authors.forename: N
authors.initials: N
authors.lastname: Hanasaki
authors.forename: D
authors.initials: D
authors.lastname: Hashimoto
authors.forename: S
authors.initials: S
authors.lastname: Iguchi
authors.forename: Y
authors.initials: Y
authors.lastname: Taguchi
authors.forename: S
authors.initials: S
authors.lastname: Miyasaka
authors.forename: Y
authors.initials: Y
authors.lastname: Tokura