Quantitative theory of superconductivity in doped C sub 60
- Max-Planck-Institut fuer Festkoerperforschung, D-7000 Stuttgart-80 (Germany)
The electronic part {eta} (the Hopfield factor) of the electron-phonon coupling constant {lambda} for alkali-metal-doped fullerenes {ital A}{sub 3}C{sub 60} is calculated within the rigid muffin-tin-potential approximation. It is found that {eta} is large for tangential atomic motions, while for the radial vibrations {eta} is 20 times smaller. We have calculated {eta} for three lattice constants ({ital a}=14.1, 14.4, and 14.6 A) corresponding approximately to those of C{sub 60}, Rb{sub 3}C{sub 60}, and (hypothetical) Cs{sub 3}C{sub 60}, and found {eta}=21, 32, and 36 eV/A{sup 2}. Using semiempirical nearest-neighbor force constants we estimated {lambda}=0.49, 0.77, and 0.83, and {l angle}{omega}{sub log}{r angle}=870 cm{sup {minus}1} for the average phonon frequency. The McMillan formula yields {ital T}{sub {ital c}}=5, 36, and 44 K for these lattice constants, in reasonable agreement with the available experimental data. The relatively high-temperature superconductivity in {ital A}{sub 3}C{sub 60}, as well as the strong dependence of {ital T}{sub {ital c}} on the dopant, is fully explained within the framework of the conventional superconductivity theory.
- OSTI ID:
- 7047122
- Journal Information:
- Physical Review, B: Condensed Matter; (United States), Journal Name: Physical Review, B: Condensed Matter; (United States) Vol. 45:9; ISSN 0163-1829; ISSN PRBMD
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360607 -- Other Materials-- Superconducting Properties-- (1992-)
665411* -- Basic Superconductivity Studies-- (1992-)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALKALI METAL COMPOUNDS
CARBON
CARBON COMPOUNDS
CESIUM COMPOUNDS
COUPLING
DOPED MATERIALS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELECTRON-PHONON COUPLING
ELEMENTS
LATTICE PARAMETERS
MATERIALS
MUFFIN-TIN POTENTIAL
NONMETALS
PHYSICAL PROPERTIES
POTENTIALS
RUBIDIUM COMPOUNDS
SUPERCONDUCTIVITY
THERMODYNAMIC PROPERTIES
TRANSITION TEMPERATURE