Magnetic properties of the ferrimagnetic cobaltite CaBaCo4O7

The magnetic properties of the ferrimagnetic cobaltite CaBaCo4O7 are systematically investigated. We find that the susceptibility exhibits a downward deviation below ∼360 K, suggesting the occurrence of short-range magnetic correlations at a temperature well above T C . The effective moment is determined to be 4.5 μ B / f.u ., which is consistent with that expected for the Co2+/Co3+ high spin species. Using a criterion given by Banerjee [Phys. Lett. 12 (1964) 16], we demonstrate that the paramagnetic to ferrimagnetic transition in CaBaCo4O7 has a first order character.