Raman scattering study of spin-density-wave-induced anisotropic electronic properties in AFe2As2 (A = Ca, Eu)...

We present a polarization-resolved and temperature-dependent Raman scattering study of AFe2As2 (A =
Ca, Eu). In the spin-density-wave phase, spectral weight redistribution is observed in the fully symmetric and
nonsymmetric scattering channels at different energies. An anisotropic Raman response is observed in the fully
symmetric channel in spontaneously detwinned CaFe2As2 samples. We calculate the orbital-resolved electronic
structures using a combination of density functional theory and dynamical mean field theory. We identify the
electronic transitions corresponding to these two spectral features and find that the anisotropic Raman response
originates from the lifted degeneracy of the dxz/yz orbitals in the broken-symmetry phase.