Spin state transition in the ferromagnet Sr0.9Ce0.1CoO2.85

The sample Sr0.9Ce0.1CoO2.85, prepared by a chemical method, has a cubic perovskite structure with lattice parameter, a=3.8368(2)Å. The effective magnetic moment obtained from temperature dependent paramagnetic susceptibility suggests that the cobalt ions, Co3+ (50%) and Co4+ (50%), are in the intermediate spin states (IS), Co3+ (t2g5eg1) and Co4+ (t2g4eg1). Further, this compound undergoes a ferromagnetic as well as a metal–metal transition at TC∼160TC∼160 K which coincides with a spin state transition of cobalt ions that is likely to be associated with the IS state of Co3+ (t2g5eg1) ions going to the low spin (LS) state (t2g6eg0) as inferred from the softening of infrared optical phonons.