Temperature and magnetic-field dependence of the ${\mathrm{Mn}}^{2+}$ ${}_{}{}^4{}_{}{}^{}$${\mathit{T}}_1$${(}^4$G)${\to }^6$${\mathit{A}}_1$${(}^6$S) photoluminescence band in ${\mathrm{Zn}}_{0.5}$${\mathrm{Mn}}_{0.5}$Se

The first and second moments of the ∼2.15-eV ${\mathrm{Mn}}^{2+}$ photoluminescence band in ${\mathrm{Zn}}_{0.5}$ ${\mathrm{Mn}}_{0.5}$Se have been measured over the temperature range 4–300 K. The first moment of the ${\mathrm{Mn}}^{2+}$ emission band shows a red shift of ∼12 meV from 4 K to the minimum at ∼45 K, followed by a blue shift of ∼40 meV up to 300 K. The band position characterized by the first moment is found to be insensitive to an externally applied magnetic field of 6 T over the entire temperature range. These observations are interpreted in terms of the ${}_{}{}^4{}_{}{}^{}$ ${\mathit{T}}_1$ ${\to }^6$ ${\mathit{A}}_1$ optical transition accompanied by a pair of spin flips of neighboring ${\mathrm{Mn}}^{2+}$ ions. This model provides the correct magnitude of the temperature-dependent red shift for T≲50 K, whereas lattice expansion accounts for the main part of the blue shift in the high-temperature regime, T≳50 K.