Investigations of even-order harmonic susceptibilities of MgB/sub 2/ superconductors using critical state approach

Even-order harmonic susceptibilities /spl chi//sub n/=/spl chi//sub n/'+i/spl chi//sub n/'' (n is even) of MgB/sub 2/ were measured at temperatures between 15 and 45 K with small ac and dc field combinations. The simplified Kim model was employed to account for the main features of the experiments by use of a fitting equation H/sub p/=H/sub /spl alpha//(1-t)/sup /spl beta// for temperature scaling. The experiments are in qualitative agreement with theory.