The project was focused on growth of single crystals of the magnetic semiconductor compounds with spinel structure MnCr₂S₄ and CoCr₂S₄. The research aimed  at  determination of correlations between the magnetic ordering and structural and electronic properties as well as at characterization of their magnetic ground state. The study was directed towards elucidating of the origin of  multiferroic behavior, of the mechanism of spin ordering in materials with different degree of frustration caused by disorder and peculiarities of their crystal structure.