Optical properties of pyrochlore oxide $P{b}_{2}R{u}_2{O}_{7-\delta }$

Abstract

We present optical conductivity spectra for $P{b}_{2}R{u}_2{O}_{7-\delta }$ single crystal at different temperatures. Among reported pyrochlore ruthenates, this compound exhibits metallic behavior in a wide temperature range and has the least resistivity. At low frequencies, the optical spectra show typical Drude responses, but with a knee feature around 1000 \cm. Above 20000 \cm, a broad absorption feature is observed. Our analysis suggests that the low frequency responses can be understood from two Drude components arising from the partially filled Ru $t_{2g}$ bands with different plasma frequencies and scattering rates. The high frequency broad absorption may be contributed by two interband transitions: from occupied Ru $t_{2g}$ states to empty $e_g$ bands and from the fully filled O 2p bands to unoccupied Ru $t_{2g}$ states.

4 pages, 6 figures