Instability of the Co magnetic state in Y2Co7-based compounds: Effect of alloying for Y- and Co-sites

High field magnetization process has been studied in the (Y1−xZrx)2Co7, (Y1−xUx)2Co7 and Y2(Co1−xAlx)7 systems in order to reveal the possibility of the transformation of the Co magnetic ions from the high to the low moment state. The spontaneous magnetic moment, Curie temperature and anisotropy constant have been found to decrease monotonously with increasing x in the single phase interval. The results suggest that the Co moment in present systems is unstable with respect to both electron concentration and exchange interactions. The average Co moment reduces to the value characteristic of the YCo3 compound. However, no signatures of the formation of the low moment Co state was found in the studied Y2Co7-based systems.