Optical properties of heusler alloys Co2FeSi, Co2FeAl, Co2CrAl, and Co2CrGa

The results of an investigation of optical properties and the calculations of the electronic structure of Co₂FeSi, Co₂FeAl, Co₂CrAl, and Co₂CrGa Heusler alloys are presented. The main focus of our attention is the study of the spectral dependence of the real part (?₁) and imaginary part (?₂) of the dielectric constant in the range of wavelengths λ = 0.3–13 μm using the ellipsometric method. An anomalous behavior of the optical conductivity σ(ω) has been found in the infrared range in the Co₂CrAl and Co₂CrGa alloys, which differs substantially from that in the Co₂FeSi and Co₂FeAl alloys. The results obtained are discussed based on the calculations of the electronic structure.