In the ferromagnetic $HgCr_2Se_4$ semiconductor ($Т_с\approx108$ K), apart from the characteristic redshift of the edge of optical absorption, a redshift of photoconductivity and photo-emf spectra was also observed with decreasing temperature. The influence of magnetic ordering on the band structure also showed itself in the temperature and magnetic field dependences of these effects. Besides the peak near $Т_с$, the dependences of the relative variation of photoelectric effects in the magnetic field on temperature exhibited an additional peak at $Т>Т_c$ for the light with an energy $h\nu$, which is close to the forbidden band width. This peak may be expected to appear in the paramagnetic region for other magnetic semiconductors, too.
Department of General Physics for the Physics Faculty, Faculty of Physics, Moscow State University, Leninskie Gory, Moscow, 119992, Russia
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