First-principles study of antiferromagnetic cobalt spinels

We report a comparative study of the electronic structure and magnetic properties of two cobalt compounds Co3O4 and Co3S4, through first-principles Hubbard-U calculations. Our results indicate that Co3O4 and Co3S4 have similarities in crystal structure (normal spinel), magnetic order (antiferromagnetism), Co spin configuration (high spin Co2+ and low spin Co3+), and comparable band-gap energy. However, the U-dependence on electronic structure in two materials are different from each other. With a change in the applied U values, the band dispersion and the type of band gap are significantly changed in Co3O4, while the band-gap energy only is affected in Co3S4.