Cobalt magnetism in RCo5-intermetallics: Onset of 3d magnetism and magnetocrystalline anisotropy (r=rare earth or Th)

Abstract In the RCo 5 compounds with trivalent R atoms, cobalt magnetism is well established. When R atoms are tetravalent (Th, Ce), the onset of 3d magnetism occurs through metamagnetism of collective electrons. This behaviour results from 3d–6d (or 5d) hybridization. The exceptionally large magnetocrystalline anisotropy of cobalt in these RCo 5 compounds is due to a large orbital contribution to the cobalt moment. An associated anisotropy of the cobalt magnetization has been measured, especially on the cobalt atoms lying on the site of uniaxial symmetry. The discontinuities in the spontaneous magnetization or the hyperfine field observed at the magnetization reorientation in such intermetallics are discussed.