We have investigated the optical and electron transport properties of superstoichiometric samarium dihydride ( SmH2 + δ ) films by measuring the room-temperature reflectivity and transmittance spectra and the temperature dependence of the DC resistivity. The reflectivity shows a minima at 1-2 eV, which is possibly due to a plasma edge. The minima show a red shift as the H/Sm ratio increases. The transmittance has a maxima at about 1 eV. The line shape of the optical conductivity cannot be explained in terms of a simple single-carrier model. In the range 0.25 < δ < 0.6, the relaxation time increases as δ increases.
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