Optical conductivity of antiferromagnetic metallic chromium: Mean-field calculation for the multi-orbital Hubbard model

The discovery of iron-pnictide superconductors has enhanced the attraction of the antiferromagnetic metallic phase of multi-orbital systems. We focus on Cr, which is representative antiferromagnetic metal with multi-orbitals like the parent iron-pnictide superconductors. We calculate the band structure and the density of states in commensurate antiferromagnetic Cr by using the spindensity wave for the multi-orbital Hubbard model in the mean-field approximation. The optical conductivity is calculated by making use of the band structure. A peak structure appears in the antiferromagnetic phase, which is consistent with experimental data. This supports the validity of our model.