A comparative ab initio study of superconductivity in the body centered tetragonal YC{sub 2} and LaC{sub 2}

Journal Article · Tue Apr 21 00:00:00 EDT 2015 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4918309· OSTI ID:22402864

Tütüncü, H. M. ^[1]; Srivastava, G. P. ^[2]

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1. Sakarya Üniversitesi, Fen-Edebiyat Fakültesi, Fizik Bölümü, 54187 Adapazarı (Turkey)
2. School of Physics, University of Exeter, Stocker Road, Exeter EX4 4QL (United Kingdom)

Ab initio studies of the electronic band structure and phonon dispersion relations, using the planewave pseudopotential method and the density functional theory, have been made for the superconducting materials YC{sub 2} and LaC{sub 2}. Differences in the phonon spectrum and density of states both in the acoustical and optical ranges between these materials are investigated and discussed. By integrating the Eliashberg spectral function α{sup 2}F(ω), the average electron-phonon coupling parameter is found to be λ = 0.55 for YC{sub 2} and 0.54 for LaC{sub 2}, indicating these to be weak-coupling BCS superconductors. It is established that about 60% of λ is contributed by acoustic phonons in both materials. Using a reasonable value of μ{sup * }= 0.13 for the effective Coulomb repulsion parameter, the superconducting critical temperature T{sub c} is found to be 3.81 K for YC{sub 2} and 2.44 K for LaC{sub 2}, in good agreement with values reported from experimental measurements.

• OSTI ID: 22402864
• Journal Information: Journal of Applied Physics, Vol. 117, Issue 15; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
COULOMB FIELD
CRITICAL TEMPERATURE
DENSITY FUNCTIONAL METHOD
DENSITY OF STATES
DISPERSION RELATIONS
ELECTRON-PHONON COUPLING
ENERGY SPECTRA
LANTHANUM CARBIDES
PHONONS
POTENTIALS
SPECTRAL FUNCTIONS
SUPERCONDUCTIVITY
SUPERCONDUCTORS