Aging and memory properties of topologically frustrated magnets

The model 2d kagomé system (H 3 O)Fe 3 (SO 4 ) 2 (OH) 6 and the 3d pyrochlore Y 2 Mo 2 O 7 are two well characterized examples of low-disordered frustrated antiferromagnets which rather then condensing into spin liquid have been found to undergo a freezing transition with spin glass-like properties. We explore more deeply the comparison of their properties with those of spin glasses, by the study of characteristic rejuvenation and memory effects in the non-stationary susceptibility. While the pyrochlore shows clear evidence for these non-trivial effects, implying temperature selective aging, that is characteristic of a wide hierarchical distribution of equilibration processes, the kagomé system does not show clearly these effects. Rather, it seems to evolve towards the same final state independently of temperature.