On the optical energy gap of SmN

The fundamental absorption edge of SmN is measured by the optical reflection and the transmission technique using a FTIR spectrometer. The MgF2 passivated thin films of SmN were grown by thermal evaporation. The optical spectra was collated in the energy range of 0.5 to 5.0 eV, and the optical energy gap is measured at 1.2 eV, the same as that of DyN. The measured value of the onset of the absorption in SmN does agree with that theoretically calculated, if the spin-orbit coupling is accounted for.