Superparamagnetic properties of La1−xBaxCoO3 (0.0<x<0.18)

The static and dynamic magnetic properties of La1−xBaxCoO3 (00.10, are also observed simultaneously. Based on the comparisons with canonical spin-glass Au96Fe4 alloy and conventional superparamagnetic (SPM) Cu97Co3 alloy, the nature of the magnetic behaviors in LBCO is ascribed to the superparamagnetic cluster rather than spin glass. Though the magnetic properties behave as SPM, LBCO has one critical point different from that of the conventional SPM Cu97Co3 alloy. The segregated Co nanoparticles in the Cu97Co3 alloy are isolated by nonmagnetic background while the clusters in LBCO are embedded in an antiferromagnetic matrix. The SPM behavior of LBCO can only exist at low temperature because the antiferromagnetic matrix transfers to paramagnetic phase at Neél temperature TN and the SPM cluster turns into ferromagnetic (FM) above TN.