The ferromagnetism of high purity ZrZn2

Measurements of magnetization at temperatures down to 4·2 °K and in fields up to 17 kOe have been made on three samples of ZrZn 2 having Fe contaminations of 25, 55 and 500 parts per million; Curie temperatures have also been determined. All three samples are ferromagnetic and have Curie temperatures of 22 °K, 21 °K and 17 °K respectively. It is suggested that ZrZn 2 is intrinsically ferromagnetic.