Synthesis and Magnetic Properties of Co1–xCuxCr2S4 (х = 0–0.6) Solid Solutions

Solid solutions of Co1–xCuxCr2S4 (х = 0–0.6), spanning the compositional range between the ferrimagnet СоCr2S4 (TC = 222 K) and the ferromagnet CuCr2S4 (TC = 377 K), were synthesized via a solid-state reaction. Their magnetic properties were studied using a AC magnetic susceptibility measurement method in the temperature range of 2–300 K under an alternating magnetic field with an amplitude of 1 Oe at various frequencies (100, 1000, 5000, and 10 000 Hz). The substitution of Co by Cu from x = 0 to x = 0.6 was found to increase the magnetic ordering temperature from 222 K to 287 K. The nature of the magnetic phase transitions was determined, revealing a transition to a frustrated spin-glass state in the sample with x = 0.05.