Optical properties of pyrochlore oxide $Pb_{2}Ru_{2}O_{7-{\delta}}$

TL;DR

This study investigates the optical conductivity of Pb2Ru2O7-δ single crystals, revealing metallic behavior, Drude responses, and interband transitions, providing insights into its electronic structure and optical properties.

Contribution

It provides the first detailed optical conductivity spectra of Pb2Ru2O7-δ, identifying multiple Drude components and interband transitions in this pyrochlore oxide.

Findings

Pb2Ru2O7-δ exhibits metallic behavior with the lowest resistivity among pyrochlore ruthenates.

Optical spectra show two Drude components with different plasma frequencies and scattering rates.

Broad absorption features are linked to interband transitions from Ru t2g to eg bands and O 2p to Ru t2g bands.

Abstract

We present optical conductivity spectra for $Pb_{2}Ru_{2}O_{7-{\delta}}$ 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.