Effects of annealing on amorphous Gdx Si1-x near the metal-insulator transition

Abstract

Annealing of amorphous Gd-Si films produces large changes in magnetic and magnetotransport properties. The materials have spin-glass freezing and enormous negative magnetoresistance (MR) in the unannealed state but show drastically reduced MR and magnetization on annealing. These changes can be explained by high resolution transmission electron micrographs and energy-dispersive x-ray analysis which show the appearance of nanocrystalline clusters of GdSi and Gd Si2 in an amorphous background. A comparison with the nonmagnetic analog Y-Si shows similar modification of electrical properties. © 2007 American Institute of Physics.