Influence of Al substitution on the structure and Co-sublattice magnetocrystalline anisotropy of Gd2Co17 compounds

The structure and magnetic properties of Gd(2)Co1(7-x)Al(x) compounds were investigated. All samples have a rhombohedral Th2Zn17-type structure and the replacement of Co by Al results in an approximately linear increase in the unit cell volumes at a rate of 8.2 Angstrom(3)/Al. The Curie temperature decreases monotically with the increase of Al concentration. On the basis of magnetization curves at the compensation temperature, the intersublattice-molecular-field coefficient, n(RT), and the RT exchange-coupling constant J(RT) have been determined. It is noteworthy that the substitution of Al has a significant effect on the magnetocrystalline anisotropy of the Co sublattice, and changes the easy magnetization direction of Gd2CO17-xAlx compounds from the basal plane to the c axis. (C) 1997 American Institute of Physics.