Magnetic properties of the layered cobaltite NdBaCo2O5.50

We present a DC magnetization, zero and longitudinal field μSR investigation on the magnetic properties of NdBaCo2O5.50. It was found that NdBaCo2O5.50 exhibits successive magnetic transitions from a high temperature paramagnetic phase to a ferromagnetic (FM) phase at TC=290(5)K, then to an antiferromagnetic (AF1) phase at TN1=265(5)K, and to another AF (AF2) phase at TN2=160(10)K. Even though the transition temperatures are similar to the ones of RBaCo2O5.5 with R=Ho, Y, Dy, Tb, the microscopic magnetic nature of NdBaCo2O5.50 is very different from the other compounds. That is, the FM phase is characterized by a temperature dependent mixture of dynamic and static phase volumes. The observed μSR frequencies indicate that in the AFM phases different spin state ordered (SSO) magnetic structures are present in NdBaCo2O5.50 than in the compounds with other rare earth ions.