Optical study of the electronic structure of locally noncentrosymmetric CeRh2As2

The electronic structures of the heavy-fermion superconductor CeRh2As2 with local inversion symmetry breaking and the reference material LaRh2As2 have been investigated by using experimental optical conductivity [sigma(1)(omega)] spectra and first-principles density functional theory calculations. The low-temperature sigma(1)(omega) spectra of LaRh2As2 revealed a broad peak at similar to 0.1 eV and a sharp peak at similar to 0.5 eV after a subtraction of the Drude contribution of free carriers. The peak features and the background intensity were nicely reproduced in calculated sigma(1)(omega) spectra from DFT calculations, implying a conventional metallic nature. In CeRh2As2, two mid-IR peaks at (h) over bar omega similar to 0.12 and 0.4 eV corresponding to the unoccupied Ce 4f(5/2) and 4f(7/2) states, respectively, were strongly developed with decreasing temperature, which suggests the emergence of hybridization states between the conduction and 4f electrons. We compared the temperature dependence of the mid-IR peaks of CeRh2As2 with corresponding data from CeCu(2)Si(2 )and CeNi2Ge2 in a ThCr2Si2-type structure to examine the possible impact of local inversion symmetry breaking on electronic structures.