Proceedings of the International Conference on Magnetism

J. Phys. Colloques 49 (1988) C8-363-C8-364
DOI: 10.1051/jphyscol:19888163

MAGNETIC ORDER IN VERY DILUTED Y-Er ALLOYS

R. Caudron^{1, 2}, H. Bouchiat³, P. J. Brown⁴, P. Monod³ et J. L. Tholence<sup>5

1</sup>  ONERA, B.P. 72, 92322 Chatillon Cedex, France
²  Laboratoire Léon Brillouin, C.E.N. Saclay, 91191 Gif sur Yvette Cedex, France
³  Laboratoire de Physique des Solides, Bât. 510, 91405, Orsay, France
⁴  Institut Laue-Langevin 39042 Grenoble, France
⁵  Centre de recherches sur les très basses températures, CNRS, B.P. 166X, 38042 Grenoble Cedex, France

Abstract
Neutron scattering and non-linear susceptibility measurements were performed on Y single crystals doped with 3, 2, 1 and 0.5 at. % Er. All the samples exhibit long range order satellites. Though Er in Y is Ising-like, no harmonics were detected. Down to T / T_N ~ 0.02, the intensities are consistent with a model where the mean magnetization of each hexagonal layer is sinusoïdally modulated in the c direction. Just above T_N, the divergence of the non linear susceptibility along the c axis behave as in a spin glass and the critical exponents γ_SG = 1 and δ_SG=2 were found. Because of the dilution, they are related to an antiferromagnetic long range order, with β_AF = 0.5 (consistent with the behaviour of the staggered magnetization), and γ_AF = 1.9.