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Non-equilibrium dynamics in a Ag(Mn) spin glass are investigated by measurements of the temperature dependence of the remanent magnetisation. Using specific cooling protocols before recording the thermo- or isothermal remanent magnetisations on re-heating, it is found that the measured curves effectively disclose non-equilibrium spin glass characteristics such as ageing and memory phenomena as well as an extended validity of the superposition principle for the relaxation. The usefulness of this "simple" dc-method is discussed, as well as its applicability to other disordered magnetic systems.Comment: REVTeX style; 8 pages, 4 figure

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Dynamic magnetic properties of Y 0.7 Ca 0.3 MnO 3 are reported. The system appears to attain local ferromagnetic order at T SRF Ϸ70 K, where SRF is short-range ferromagnetism. Below this temperature the low-field magnetization becomes history dependent, i.e., the zero-field-cooled ͑ZFC͒ and field-cooled magnetization deviate from each other and close logarithmic relaxation appears at our experimental time scales (0.3-10 4 sec). The zero-field-cooled magnetization has a maximum at T f Ϸ30 K, whereas the field-cooled magnetization continues to increase, although less sharply, also below this temperature. Surprisingly, the dynamics of the system show nonequilibrium spin-glass features not only below the maximum in the ZFC magnetization, but also in the temperature region between this maximum and T SRF . The aging and temperature cycling experiments show only quantitative differences in the dynamic behavior above and below the maximum in the ZFC magnetization; similarly, memory effects are observed in both temperature regions. We attribute the high-temperature behavior to the existence of clusters of short-range ferromagnetic order below T SRF ; the configuration evolves into a conventional spin-glass state at temperatures below T f .