I am confused about the magnetic susceptibility vs. temperature curves (or MT) of superconductors (SCs). In the normal conduction state (I measured from 4.5K to 300K), the susceptibility curve can obey the Curie-Weiss law. But when I fitted the data via the Curie-Weiss law in a different temperature range, different results (effective magnetic moment) came out. How should I select the temperature range in the normal state for fitting the curves with the Curie-Weiss law? Also, I synthesized a series of SC samples with different Tc. How should I compare the susceptibility curves of SCs with different Tc? What physical properties can be concluded form those MT curves?