Ferromagnetic/Helimagnetic Rare Earth Gd-Dy Superlattices

We report the long range magnetic order of the inter magnetic rare earth Gd-Dy superlattice, where each bilayer period contains ferromagnetic Gd planes followed by helimagnetic Dy planes. The magnetic correlations between successive Gd arrays via intervening Dy helix are compared with the properties obtained earlier in the Dg-Y superlattices with comparable wavelengths and compositions. The magnetic moment vs temperature measured by a SQUID susceptometer on one (10,22) sample showed at 100 Oe the initial increase of Gd moment below Tc=285 K, and subsequently rapid decrease of Gd moment below 200K. The behavior is consistent with the picture in that a helical rotation of spins is formed between the successive Gd arrays. Further magnetization measurements along with neutron diffraction studies are underway.