Zusammenfassung
The frequency dependence of the freezing temperatureT f(ν) is determined for the dilute spin glass systems (La, Gd)B6 and (Y, Gd)Al2 in the frequency range 10–1,000 Hz. While for (La, Gd)B6,T f(ν) is found to be weak, for (Y, Gd)Al2 T f(ν) is even stronger than for the previously studied system (La, Gd)Al2. Both, measurements of the temperature dependence of the susceptibility nearT f and calculations of the RKKY pair interaction, suggest that this difference is correlated with a different sign of the nearest-neighbor interaction, which appears to be antiferromagnetic for (La, Gd)B6 and ferromagnetic for (Y, Gd)Al2 as well as (La, Gd)Al2.