Magnetic Properties of Fe1 – xCoxCr2S4 Solid Solutions in the FeCr2S4-Rich Region

The magnetic susceptibility of Fe_{1 – x}Co_xCr₂S₄ solid solutions in the FeCr₂S₄-rich part of the FeCr₂S₄–CoCr₂S₄ system has been studied by static and dynamic methods. The magnetic measurements were performed at temperatures from 5 to 300 K in static (50 Oe and 45 kOe) and ac magnetic fields (field amplitude H_ac = 1 Oe; ac field frequencies ν = 100, 1000, and 10 000 Hz). We have determined the temperatures of the magnetic transformations in the system and identified their nature. The results demonstrate that the temperature of the ferrimagnetic phase transition (T_C) in Fe_{1 – x}Co_xCr₂S₄ increases with increasing cobalt content. The materials with x = 0–0.5 have been shown to undergo a transition to a spin glass state, evidenced by a shift of maxima in temperature dependences of the imaginary part of their dynamic susceptibility.