Extended x-ray-absorption fine-structure studies ofZn1−xMnxSe alloy structure

Bond lengths, Debye-Waller factors, and site occupancy in the diluted magnetic semiconductor ${\mathrm{Zn}}_{1\mathrm{-}\mathit{x}}$ ${\mathrm{Mn}}_{\mathit{x}}$Se have been measured using extended x-ray-absorption fine structure. The nearest-neighbor bond lengths at both room temperature and low temperature (77 K) are found to be constant as a function of alloy composition within the experimental uncertainty of 0.01 Å. Because the average cation-cation distance changes with Mn content, these results necessarily imply distortion of the tetrahedral bond angles. The anion sublattice is shown to suffer the largest distortion, but the cation sublattice also exhibits some relaxation. The repercussions of these results are discussed, in terms of the amount of cation and anion sublattice distortion at low temperature and its connection to the superexchange mechanism occurring between the ${\mathrm{Mn}}^{2+}$ ions and mediated by the intervening anion in ${\mathrm{Zn}}_{1\mathrm{-}\mathit{x}}$ ${\mathrm{Mn}}_{\mathit{x}}$Se.