Based on a two-band model, we study the electronic Raman scattering intensity in both normal and superconducting states of iron-pnictide superconductors. For the normal state, due to the match or mismatch of the symmetries between band hybridization and Raman vertex, it is predicted that overall $B_{ 1g}$ Raman intensity should be much weaker than that of the $B_{ 2g}$ channel. Moreover, in the non-resonant regime, there should exhibit a interband excitation peak at frequency $\omega\simeq 7.3 t_1 (6.8t_1)$ in the $B_{ 1g}$ ($B_{ 2g}$) channel. For the superconducting state, it is shown that $\beta$-band contributes most to the $B_{ 2g}$ Raman intensity as a result of multiple effects of Raman vertex, gap symmetry, and Fermi surface topology. Both extended $s$- and $d_{ xy}$-wave pairings in the unfolded BZ can give a good description to the reported $B_{ 2g}$ Raman data [Muschler { \em et al.}, Phys. Rev. B. { \bf 80}, 180510 (2009).], while $d_{ x^2-y^2}$-wave pairing in the unfolded BZ seems to be ruled out.
Categories: cond-mat.supr-con cond-mat.str-el