Spin-glass freezing and RKKY interactions near the metal-insulator transition in amorphous Gd-Si alloys
Magnetization measurements of giant negative magnetoresistive amorphous GdxSi1-x ( 0.04<x<0.19) show strong mixed ferromagnetic and antiferromagnetic interactions and spin-glass freezing. The interactions appear to be an RKKY-like indirect exchange mediated by the conduction electrons, but are strikingly independent of their localization at the metal-insulator (MI) transition, presumably because the localization length exceeds the inter-Gd distance. The susceptibility per Gd atom in the paramagnetic state shows a nontrivial dependence on composition, with a maximum at the MI transition.
Hellman
F
Department of Physics, University of California, San Diego, California 92093, USA.
Queen
DR
Potok
RM
Zink
BL