Optical properties of $MgCN{i}_3$ in the normal state

Abstract

We present the optical reflectance and conductivity spectra for non-oxide antiperovskite superconductor $MgCN{i}_3$ at different temperatures. The reflectance drops gradually over a large energy scale up to 33,000 cm${}^{-1}$, with the presence of several wiggles. The reflectance has slight temperature dependence at low frequency but becomes temperature independent at high frequency. The optical conductivity shows a Drude response at low frequencies and four broad absorption features in the frequency range from 600 $c{m}^{-1}$ to 33,000 $c{m}^{-1}$. We illustrate that those features can be well understood from the intra- and interband transitions between different components of Ni 3d bands which are hybridized with C 2p bands. There is a good agreement between our experimental data and the first-principle band structure calculations.

4 pages, to be published in Phys. Rev. B