Helimagnetic structure in diluted Y-Gd alloys

Neutron scattering studies on Y-Gd 2 and 3 at. % single crystals show a helimagnetic ordering to occur below Neel temperatures of 7 and 12 K respectively. The same value of the propagation vector [0, 0, 0.28 c*] is obtained for both samples. The Gd moments lie in the basal plane of the hexagonal structure. No contribution from the conduction electrons to the magnetic amplitudes is evidenced in addition to the 4f contribution. The Gd moment at low temperature is about 7 μg. The temperature dependence of the magnetic satellite intensity follows that predicted by a Brillouin function L'etude par diffraction de neutrons de Y-2% Gd et Y-3% Gd monocristallins revele un ordre helimagnetique au-dessous du point de Neel. On obtient une meme valeur du vecteur de propagation pour les deux echantillons. Les moments de Gd sont dans le plan de base de la structure hexagonale. Aucune contribution des electrons de conduction aux amplitudes magnetiques n'apparait superposee a la contribution 4f