Imaginary part of the optical conductivity of Ba{sub 1{minus}{ital x}}K{sub {ital x}}BiO{sub 3}

Journal Article · Mon Apr 01 04:00:00 EST 1996 · Physical Review, B: Condensed Matter

DOI:https://doi.org/10.1103/PhysRevB.53.9433· OSTI ID:280205

Marsiglio, F ^[1]; Carbotte, J P ^[2]; Puchkov, A ^[2]; Timusk, T ^[2]

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1. Neutron and Condensed Matter Science, Atomic Energy of Canada Limited, Chalk River Laboratories, Chalk River, Ontario, Canada KOJ1JO
2. Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, L8S4M1 (CANADA)

The frequency dependence of the imaginary part of the infrared conductivity is calculated for a superconductor. Sharp structure, characteristic of superconductivity with an order parameter with {ital s}-wave symmetry, appears in the BCS limit as a minimum at a frequency equal to twice the gap value. This structure scales with temperature but gets progressively smeared and shifted as impurity scattering is increased. The relationship between low-frequency results and the zero-frequency limit is investigated. Experimental results on Ba{sub 1{minus}{ital x}}K{sub {ital x}}BiO{sub 3} are also presented. The low-frequency imaginary part of the conductivity displays a minimum at 2{Delta}{approx_equal}12 meV, and provides unequivocal evidence of an {ital s}-wave superconducting order parameter. Strong-coupling (Eliashberg) results show similar trends. Using this formulation we find that the electron-phonon coupling in Ba{sub 1{minus}{ital x}}K{sub {ital x}}BiO{sub 3} must necessarily be small, with coupling constant {lambda}{approx_equal}0.2, in agreement with conclusions drawn from measurements of the real part of the conductivity. Thus Ba{sub 1{minus}{ital x}}K{sub {ital x}}BiO{sub 3} is an {ital s}-wave superconductor that is not driven by the conventional electron-phonon interaction. {copyright} {ital 1996 The American Physical Society.}

• OSTI ID: 280205
• Journal Information: Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 14 Vol. 53; ISSN PRBMDO; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
BARIUM OXIDES
BISMUTH OXIDES
ELECTRON-PHONON COUPLING
FREQUENCY DEPENDENCE
ORDER PARAMETERS
PHOTOCONDUCTIVITY
POTASSIUM OXIDES
S WAVES
SUPERCONDUCTORS