Two-band model of Raman scattering on iron pnictide Ba(Fe1-xCox)2As2Ba(Fe1-xCox)2As2 superconductors

• Electronic Raman scattering is theoretically studied for iron-pnictide superconductors.
• Key features are given/predicted both in normal and superconducting states.
• Fittings to the B1gB1g data [11] are made for various pairing models and conclusion are drawn.

Based on a two-band model, we theoretically study the electronic Raman scattering spectra in both normal and superconducting states of iron-pnictide Ba(Fe1-xCox)2As2Ba(Fe1-xCox)2As2 superconductors. In the normal state, due to the match or mismatch of band hybridization and Raman vertex symmetries, overall B2gB2g Raman intensity is found to be much stronger than that of the B1gB1g channel. Besides, in the non-resonant limit, there could exhibit an interband excitation peak at high frequency ω≃7.3t1(6.8t1)ω≃7.3t1(6.8t1) in the B1gB1g (B2gB2g) channel with t1t1 the nearest-neighbor hopping. In the superconducting state, due to the composite effect of Raman vertex, gap symmetry, and Fermi surface topology, both B1gB1g and B2gB2g Raman intensities are dominated by αα- (ββ-) band contribution for the extended s  -wave (dx2-y2dx2-y2-wave) pairing, whereas both bands are equally important for the s±s±-wave pairing. It is shown that both extended s  - and s±s±-wave pairings can lead to a good fitting for the reported B1gB1g data Muschler et al. (2009) [11], while the dx2-y2dx2-y2-wave pairing seems not favorable.