Charge dynamics near the electron-correlation induced metal-insulator transition in pyrochlore-type molybdates.
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.
Kézsmárki
I
I
Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan.
Hanasaki
N
N
Hashimoto
D
D
Iguchi
S
S
Taguchi
Y
Y
Miyasaka
S
S
Tokura
Y
Y