Magnetic States of Fe2+ Ions in FexMn1 – xS Induced by Chemical Pressure

Influence of the chemical pressure ( x ) in single crystals of Fe x Mn 1 – x S (0.12 ≤ x ≤ 0.29) on the spin state of iron ions was studied by Mössbauer spectroscopy in the temperature range from 4.2 to 300 K. Peculiarities of formation of the paramagnetic and antiferromagnetic phases of solid solutions were found. Substitution of Fe 2+ cations in the high-spin state for Mn 2+ was found to occur in Fe x Mn 1 – x S as x changes. A decrease in the distance between the ions in Fe x Mn 1 – x S induces changes in the state of the Fe 2+ ions in the samples with x = 0.25 and 0.29. The asymmetry parameter of the electric field gradient (EFG) tensor and the angle between the directions of the magnetic moment and the principal axis of the electric field gradient were found to change in the magnetically ordered phase at 4.2 K; the angle between the magnetic moment and the electric field gradient axis changes from 21° in the sample with x = 0.12 to 33° when x = 0.29.