Comparative optical reflectance study of the superconducting KHg-graphite and CsBi/sub x/-graphite intercalation compounds

Journal Article · Mon Feb 01 04:00:00 EST 1988 · Phys. Rev. B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.37.1711· OSTI ID:5529664

Yang, M H; Charron, P A; Heinz, R E; Eklund, P C

We report the results of a comparative optical reflectance study at room temperature of the stage-1 and stage-2 CsBi/sub x/ and KHg graphite intercalation compounds (GIC's) in the energy range 0.2--10 eV. A Kramers-Kronig analysis is carried out to determine the dielectric function epsilon(..omega..) = epsilon/sub 1/(..omega..)+epsilon/sub 2/(..omega..) and the intra- and interband contributions to epsilon(..omega..) are identified. The dielectric function for the respective compounds are analyzed in terms of a schematic density-of-states model involving contributions from two-dimensional graphite ..pi.. band(s) and intercalate bands. Separate contributions from the ..pi.. and intercalate electrons to the free-carrier plasma frequency are determined via the identification of the carbon ..pi --> pi../sup */ interband absorption threshold E/sub T/approx.2E/sub F/, where E/sub F/ is the Fermi energy measured with respect to the approximate mirror plane in the carbon ..pi..-band structure. The analysis of the optical data indicates that for CsBi/sub x/ GIC's, the electrical transport properties should be dominated by the light carbon ..pi..-band electrons in contrast to the KHg GIC's, where the analysis indicates the transport properties should strongly depend on free carriers in both the ..pi../sup */ and the intercalate band(s). In the case of KHg GIC's, our interpretation of the experimental results are consistent with significant occupation of electronic states with Hg(6s) character. Our results suggest that nature of the superconductivity in the KHg and CsBi/sub x/ GIC's should be quite different.

• Research Organization: Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506
• OSTI ID: 5529664
• Journal Information: Phys. Rev. B: Condens. Matter; (United States), Journal Name: Phys. Rev. B: Condens. Matter; (United States) Vol. 37:4; ISSN PRBMD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360603* -- Materials-- Properties
ALKALI METAL COMPOUNDS
BISMUTH COMPOUNDS
CARBON
CESIUM COMPOUNDS
CORRELATIONS
DIELECTRIC PROPERTIES
ELECTRICAL PROPERTIES
ELECTRONIC STRUCTURE
ELEMENTAL MINERALS
ELEMENTS
ENERGY RANGE
ENERGY-LEVEL DENSITY
EV RANGE
EV RANGE 01-10
GRAPHITE
KRAMERS-KRONIG CORRELATION
MEDIUM TEMPERATURE
MERCURY COMPOUNDS
MILLI EV RANGE
MINERALS
NONMETALS
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
POTASSIUM COMPOUNDS
REFLECTIVITY
SUPERCONDUCTORS
SURFACE PROPERTIES