Abstract
Polycrystalline thin films of the ferromagnetic semiconductor HgCr2Se4 have been prepared for the first time on insulating MgAl2O4 single crystal substrates by molecular beam deposition and subsequent annealing with HgSe.
Measurements of absorption spectra for the thin films of HgCr2Se4 were made at 295, 95 and 25 K in the photon energy from 0.5 to 3.0 eV. It becomes evident that there exists an absorption band with a maximum at about 0.93 eV at 295 K. This absorption band shows a red-shift phenomenon, with decreasing temperature, corresponding to the transition from the valence band to the narrow conduction band which is caused by s-d interaction and s-d hybridization. Furthermore, we found that there exist other transitions with energy gaps of 1.20, 1.47 and 1.90 eV at 295 K.
As a result of this investigation we point out the possibility of making tunable lasers from this material.
