Perfect separation of intraband and interband excitations in PdCoO2

The temperature dependence of the optical properties of the delafossite PdCoO2 has been measured in the a-b planes over a wide frequency range. The optical conductivity due to the free-carrier (intraband) response falls well below the interband transitions, allowing the plasma frequency to be determ...

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Bibliographic Details
Published in:Physical review. B 2019-05, Vol.99 (19), p.195127
Main Authors: Homes, C Homes, Khim, S, Mackenzie, A P
Format: Article
Language:English
Subjects:
CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
Density functional theory
Frequency ranges
Mathematical analysis
Optical properties
Plasma
Plasma frequencies
Scattering
Temperature dependence
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Summary:The temperature dependence of the optical properties of the delafossite PdCoO2 has been measured in the a-b planes over a wide frequency range. The optical conductivity due to the free-carrier (intraband) response falls well below the interband transitions, allowing the plasma frequency to be determined from the f-sum rule. Drude-Lorentz fits to the complex optical conductivity yield estimates for the free-carrier plasma frequency and scattering rate. The in-plane plasma frequency has also been calculated using density functional theory. The experimentally determined and calculated values for the plasma frequencies are all in good agreement; however, at low temperature the optically determined scattering rate is much larger than the estimate for the transport scattering rate, indicating a strong frequency-dependent renormalization of the optical scattering rate. In addition to the expected in-plane infrared-active modes, two very strong features are observed that are attributed to the coupling of the in-plane carriers to the out-of-plane longitudinal optic modes.
ISSN:2469-9950
2469-9969
DOI:10.1103/PhysRevB.99.195127