Magnetic aging and non-equilibrium dynamics in Y0.7Ca0.3MnO3

Dynamic magnetic properties of Y0.7Ca0.3MnO3 are reported. The system appears to enter a state governed by short-range ferromagnetic correlations at Tcg∼70 K. Below this temperature the low-field magnetization becomes history dependent, i.e. the zero-field-cooled (ZFC) and field-cooled (FC) magnetization deviate from each other. The ZFC magnetization shows a maximum at Tf∼30 K. Surprisingly, the dynamics of the system shows non-equilibrium spin-glass features not only below the maximum in the ZFC magnetization, but also in the temperature region between this maximum and Tcg. We interpret the behaviour to support the existence of clusters of short-range ferromagnetic order below Tcg, which evolves into a conventional spin-glass phase at temperatures below Tf