Metal-insulator transition in FexMn1-xS crystals

Results of an experimental study of MnS, FeS, and FexMn1-xS single crystals are presented. The phase composition, the lattice parameters, and the state of paramagnetic ions in FexMn1-xS have been determined by x-ray diffraction analysis and Mossbauer spectroscopy. A sequence of transitions have been found in iron manganese sulfide with x = 0.29 at temperatures T-1 approximate to 25-50 K, T-2 approximate to 125 K, and T-3 approximate to 190 K with a change in kinetic properties and the formation of a metallic state at low temperatures T approximate to 2 K. The possibility of a Mott-Hubbard transition in FexMn1-xS sulfides with variation of the composition and the temperature is discussed.