Tunable exchange-bias and magnetic compensation temperature of two-phase spinel composites (1 − x) (Co₃O₄) + x (Co₂TiO₄)

We report a detailed compositional dependence of magnetic interactions in (1 − x) (Co₃O₄) + x (Co₂TiO₄) [0 ≤ x (wt.%) ≤ 100] two-phase oxide spinels. Variation of ferrimagnetic Néel temperature (T_N) was observed within 53.5–47.4 K by varying the composition from x = 0.23 to 1.0. For T < T_N, the temperature dependence of dc susceptibilities curves (χ(T) vs T) in both zero-field-cooled (ZFC) and field-cooled (FC) measurements exhibited the magnetic-compensation (T_COMP) phenomena due to the complete magnetization balance of tetrahedral and octahedral sublattices. Further, we noticed a gradual decrease in T_COMP from 37.71 K to 31.74 K with increasing x. A high value of coercivity H_C (~19 kOe for x = 0.23) and exchange bias H_EB (≈ 887 Oe for x = 1.0) was observed below T_N, which can be tuned with x. The plausible origins of the large H_C and H_EB and the associated magnetic interactions are presented.