Imaginary part of the optical conductivity of Ba{sub 1{minus}{ital x}}K{sub {ital x}}BiO{sub 3}
- Neutron and Condensed Matter Science, Atomic Energy of Canada Limited, Chalk River Laboratories, Chalk River, Ontario, Canada KOJ1JO
- 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
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