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- Title
Multi-gap superconductivity in a BaFeCoAs film from optical measurements at terahertz frequencies.
- Authors
Perucchi, A.; Baldassarre, L.; Lupi, S.; Jiang, J. Y.; Weiss, J. D.; Hellstrom, E. E.; Lee, S.; Bark, C. W.; Eom, C. B.; Putti, M.; Pallecchi, I.; Marini, C.; Dore, P.
- Abstract
We measured the THz reflectance properties of a high quality epitaxial thin film of the Fe-based superconductor BaFeCoAs with T = 22.5 K. The film was grown by pulsed laser deposition on a DyScO substrate with an epitaxial SrTiO intermediate layer. The measured R/ R spectrum, i.e. the reflectivity ratio between the superconducting and normal state reflectance, suggests the presence of a superconducting gap Δ close to 15 cm. A detailed data analysis shows that a two-band, two-gap model is necessary to obtain a good description of the measured R/ R spectrum. The low-energy Δ gap results to be well determined ( Δ = 15.5 ±0.5 cm), while the value of the high-energy gap Δ is more uncertain ( Δ = 55 ±7 cm). Our results provide evidence of two electronic contributions to the system conductivity with the presence of two optical gaps corresponding to 2 Δ/ kT values close to 2 and 7.
- Subjects
REFLECTANCE; THIN films; SUPERCONDUCTORS; SUPERCONDUCTIVITY; PULSED laser deposition
- Publication
European Physical Journal B: Condensed Matter, 2010, Vol 77, Issue 1, p25
- ISSN
1434-6028
- Publication type
Article
- DOI
10.1140/epjb/e2010-00242-y