Observation of superficial antiferromagnetism in Co3O4 polycrystals

Abstract: We report on a systematic study about the magnetic properties of Co3O4 polycrystals with large size distribution (100-1200 nm) and the crystallite size of 68(4) nm on average. An antiferromagnetic transition at TN = 32 K, extensively reported in the literature for Co3O4, was observed. Furthermore, another transition at Tt = 14 K, which is suppressed for H >= 35 kOe, was also identified. An increase in the magnetic susceptibility, as well as irreversibility between zero field cooled and field cooled data below Tt were observed. The non-detection of a coercive field below Tt, and the fact that Tt and TN are independent from the driven frequencies in ac magnetic measurements as a function of temperature, confirm that both peaks are associated to antiferromagnetic transitions.

Author(s): von Dreifus, D; Pereira, EC ; de Oliveira, AJA

MATERIALS RESEARCH EXPRESS