Magnetic Transition in the Perovskite Ba2CoNbO6

The crystal structure of Ba2CoNbO6 perovskite has been studied and was found to be cubic Pm m with a random occupation of the Co3+ and Nb5+ ions at the same crystallographic site. DC susceptibility–temperature (CHI–T) curves exhibit weak ferromagnetic transitions at 43–47 K. The transition becomes less sharp as the applied field is increased up to 50000 Oe. Finally, the transition disappears in a field of H=50000 Oe. From the logarithmic time dependence of the magnetization at 5 K, this behavior is ascribed to the formation of spin-glass or cluster-glass states, which are induced by the magnetic frustration due to the intermediate-spin (IS) state of Co3+.