Broadband optical conductivity of the chiral multifold semimetal PdGa

We present an optical conductivity study of the multifold semimetal PdGa, performed in a broad spectral range (100 – 20 000 cm−1; 12 meV–2.5 eV) down to T = 10 K. The conductivity at frequencies below 4000 cm − 1 is dominated by free carriers while at higher frequencies interband transitions provide the major contribution. The spectra do not demonstrate a significant temperature evolution: Only the intraband part changes as a function of temperature with the plasma frequency remaining constant. The interband contribution to the conductivity exhibits a broad peak at around 5500 cm−1 and increases basically monotonously at frequencies above 9000 cm−1. The band-structure-based computations reproduce these features of the interband conductivity and predict its linear-in-frequency behavior as frequency diminishes.