Charge dynamics near the electron-correlation induced metal-insulator transition in pyrochlore-type molybdates

Phys Rev Lett. 2004 Dec 31;93(26 Pt 1):266401. doi: 10.1103/PhysRevLett.93.266401. Epub 2004 Dec 20.

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.