The localization of magnetic moment in PrNi4Cu ferromagnet

The crystallographic and the magnetic structures of PrNi4Cu compound have b een studied by means of neutron powder diffraction. It is shown that the Ni -ions prefer 3g site strongly, and Cu ions occupy 2c ones of the CaCu5-type hexagonal structure. An anisotropic lattice expansion (Delta a/a = 0.08%) is observed while the temperature decreases from 10 to 1.5 K. A long-range ferromagnetic order with the propagation vector k = 0 is revealed at 1.5 K. The magnetic moments are localized on Pr-ions only and aligned in the basa l plane. The value of the magnetic moment is 0.50(18)mu(B)/Pr-ion. It is as sumed that the magnetic ordering appears in PrNi4Cu due to the mixing of th e ground and excited states of Pr3+ ions. (C) 2000 Elsevier Science B.V. Al l rights reserved.