Evidence of two distinct dynamical freezing processes in single-layered perovskite La0.7Sr1.3CoO4

The static and dynamic features of magnetization have been investigated in terms of dc magnetization, ac susceptibility, and memory effects on single-layered perovskite La0.7Sr1.3CoO4. The results indicate that short-range ferromagnetic clusters coexist with the glassy magnetic state, i.e., a cluster-glass phase between Tf and TG and a spin-glass-like phase below Tf. The clear evidence of memory effects in the dc magnetization is also observed below Tf and TG, respectively. These two glassy states with cooperative relaxation processes may derive from the different interaction processes among nanoscale ferromagnetic clusters mediated by the matrix, which is influenced by changing the spin state of Co3+ ions in spontaneously phase-separated cobaltite.