Optical properties and the electronic structure of Co2TiGe and Co2TiSn Heusler alloys

The frequency dependences of the real part ε₁(ω) and imaginary part ε₂(ω) of the complex dielectric constant of the Heusler alloys Co₂TiGe and Co₂TiSn have been studied in the spectral range of 0.1–5 eV. It has been established that the interband electron transitions play a dominant role in the formation of the optical properties of these alloys. An anomalous behavior of the optical properties in the IR range of spectrum, namely, the absence of the Drude component of the optical conductivity σ(ω), has been revealed. The results of the studies have been discussed based on the calculations of the electronic structure of the alloys.