Spectroscopic evidence of spinel phase clustering in solid solutions Hg1-x CrxSe (0.03 ≤ x ≤ 0.1)

The diluted magnetic semiconductors Hg1-xCrxSe (0.03 <= x <= 0.1) were prepared by the solid state recrystallization method. The structure microanalysis of the Hg1-xCrxSe compounds, performed by using a scanning electron spectrometer, has shown that the HgCr2Se4 spinel-like inclusions are present in the host matrix Hg1-xCrxSe and their amount increases when the chromium content grows. ESR studies of Hg1-xCrxSe samples were carried out in the temperature range 4.2-300 K. ESR spectra of the samples with different chromium contents demonstrate the same g-factors at room temperature and similar fine structure development with the temperature decrease. Numerical studies of g-factors, performed by the modified crystal field approach (MCFA), allowed us to reveal that Cr2+/Cr3+ ions in the tetrahedral environment of the solid solution Hg1-xCrxSe cannot lead to the ESR signal. The experimental g-factor is well reproduced by a numerical g-factor for Cr3+ ions located in the octahedral environment, being specific for the HgCr2Se4 spinel phase. The onset of the ESR fine structure is determined by the trigonal distortions of the (CrSe6)(9-) octahedral cell. From our study it has been found that the spinel clusters are present in the Hg1-xCrxSe solid solution even at low chromium content.