  Experiments on the time dependence of the response function of a Ag(11 at%Mn)
spin glass at a temperature below the zero field spin glass temperature are
used to explore the non-equilibrium nature of the spin glass phase. It is found
that the response function is only governed by the thermal history in the very
neighbourhood of the actual measurement temperature. The thermal history
outside this narrow region is irrelevant to the measured response. A result
that implies that the thermal history during cooling (cooling rate, wait times
etc.) is imprinted in the spin structure and is always retained when any higher
temperature is recovered. The observations are discussed in the light of a real
space droplet/domain phenomenology. The results also emphasise the importance
of using controlled cooling procedures to acquire interpretable and
reproducible experimental results on the non-equilibrium dynamics in spin
glasses.
