Structural and magnetic properties of Gd(Cosub(x)Irsub(1-x))2

The crystal structure and magnetic properties of the pseudobinary system Gd(Cosub(x)Irsub(1-x))2 are reported. The compounds crystallise in the C15 Laves phase with a sudden lattice contraction at x = 0.4. Magnetic measurements indicate that Co develops a magnetic moment for x > 0.4. The onset of this moment is coincident with a sudden contraction of the lattice. Electron spin resonance measurements of g shift and linewidth also show sharp increases at x = 0.4. The correlated changes in the various properties are interpreted as due to a movement of the Fermi level as Co is substituted for Ir. (author)