Optical properties of BaFe1.85 Co 0.15 As 2
Abstract
The detailed in-plane optical properties of the electron-doped iron-arsenic superconductor BaFe 1.85 Co 0.15 As 2 have been determined over a wide frequency range above and below Tc = 25 ~K. Despite being a multiband system, the normal state reveals that a single (electron) band dominates the low-frequency conductivity, which can be modeled by a single Drude component with plasma frequency ωp , D ~= 7840 ~cm-1 and scattering rate 1 /τD ~= 126 ~cm-1 , determined just above Tc . For T <<Tc the superconducting plasma frequency is ωp , S ~= 5200 ~cm-1 (λeff ~= 3000 ~Å), indicating that less than half the free carriers in the normal state have collapsed into the condensate, suggesting that this material is not in the clean limit. There are two energy scales for the superconductivity, Δ1 (0) = 3.1 +/- 0.2 ~meV and Δ2 (0) = 7.4 +/- 0.3 ~meV. This corresponds to either the gapping of the electron and hole pockets, respectively, or an anisitropic s-wave gap on the electron pocket; both views are consistent with the s+/- model.
Supported by the DOE under Contract No. DE-AC02-98CH10886.- Publication:
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APS March Meeting Abstracts
- Pub Date:
- March 2011
- Bibcode:
- 2011APS..MARQ26005T