Additionally to the data recorded upon cooling, we have investigated the T-dependent susceptibilities of both samples upon heating in a field-cooled (FC) and zero-field-cooled (ZFC) scan (Fig. ). For both compounds the ZFC and FC data deviate from the cooling data below 90 K. The ZFC and FC curves of 2-Tb remain on top of each other below 90 K until they separate around 15 K. This separation can be interpreted as a hint of magnetic blocking at this temperature. Both curves have an intense, sharp maximum at approximately 11 K (FC) and 12 K (ZFC). For 3-Tb, both ZFC and FC data show a broad maximum around 50 K. In the T range from 90 K -30 K, the susceptibility values are very comparable between the FC and ZFC measurements while they deviate below 30 K (Fig. ). It should be noted that the splitting between ZFC and FC data is much less pronounced than in 2-Tb. While temperature dependent susceptibility data can provide an idea about the magnetic relaxation behavior, dynamic AC susceptibility measurements allow a much greater insight.