Field-induced exchange effects in (Cd,Mn)Te and (Cd,Mn)Se from photoluminescence measurements

Photoluminescence measurements are made on the semimagnetic semiconductors ${\mathrm{Cd}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{Mn}}_{\mathrm{x}}$Te and ${\mathrm{Cd}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{Mn}}_{\mathrm{x}}$Se for 0<x≤0.15. Large energy shifts (∼50 meV) of the exciton recombination peaks and large optical polarizations (∼100%) are produced by applying a magnetic field. This study examines changes in luminescence using magnetic fields up to B=15 T and at temperatures between T=1.5 and 60 K. When viewed along the direction of the field (Faraday geometry), the luminescence due to both exciton recombination and impurity-related transitions becomes circularly polarized. At T=2 K the polarization shows saturation at only 0.5 T.