High-field magnetisation of SmCo5−xCux (x≈2.5) determined in pulse fields up to 48T

Abstract The strong influence of Cu substitution on the magnetic properties of SmCo 5 , especially on the coercive field, is well known. Induction-melted samples ( x = 2 , 2.5 , 3 ) show a phase separation within the 1:5 structure. An unusual jump from a low to a high magnetisation state in an increasing external field is observed. Using pulse field, high coercive forces up to about μ 0 J H c ≈30 T and a high critical field μ 0 H U for the unusual jump reaching 45 T at 4.2 K for x = 3 are observed for the first time. H c and H U increase with decreasing temperature. An influence of the field changing rate on the measured H U is found.