Electronic Properties of Magnetic Semiconductor Compounds TlFeS2 and TlFeSе2

The electronic properties of magnetic semiconductors TlFeS₂ and TlFeSе₂ have been investigated experimentally by spectral ellipsometry and theoretically ab initio using the density functional theory (DFT). The imaginary and real parts of the dielectric function and the dispersion of the refractive indices, extinction coefficients, and absorption coefficients are found from ellipsometric measurements in the energy range of 0.7−6.5 eV. The direct band gap is estimated. The band structure, the origin of energy states, the optical functions, and the partial densities of states (PDOS) projected on atoms are determined from ab initio calculations. The calculation results are compared with the spectral ellipsometry data obtained in this study.