Characterization and electronic structure calculations of the antiferromagnetic insulator Ca3 FeRh O6

We investigate the antiferromagnetic insulating nature of Ca3 FeRh O6 both experimentally and theoretically. Susceptibility measurements reveal a Néel temperature of TN 20 K and an effective magnetic moment of 5.3 μB fu. Mössbauer spectroscopy strongly suggests that the Fe ions, located at trigonal prismatic sites, are in a 3+ high-spin state. Transport measurements display a simple Arrhenius law, with an activation energy of ∼0.2 eV. The experimental results are interpreted with local spin-density approximation band-structure calculations, which confirm the Fe3+ state, the high-spin versus low-spin scenario, the antiferromagnetic ordering, and the value for the activation energy.