Optical spectroscopy of intermetallic compounds TbNi$_{2}$Mn$_{x}$ ($x$ = 0, 0.5, 1)

The optical properties of intermetallic compounds TbNi$_{2}$Mn$_{x}$ ($x$ = 0, 0.5, 1) have been investigated using the ellipsometric method in the spectral range from 0.22 to 16 $\mu$m. The specific features of the modification of the dispersions of spectral characteristics with a variation in the manganese concentration have been determined. The behavior of the frequency dependences of the optical conductivity in the interband absorption region has been discussed in terms of the available data on the electronic structure of these compounds. The concentration dependences of a number of electronic parameters have been calculated.