MAGNETIC AND ELECTRICAL-PROPERTIES OF THE PSEUDO-BINARY GDCU5-XALX COMPOUNDS

The effect of substitution of Al for Cu on the lattice parameters, and the magnetic and electrical properties of the GdCu5-xAlx compounds ha s been studied. The behaviour of the compounds with low Al concentrati on (0 less than or equal to x less than or equal to 0.5) differs marke dly from that of the compounds with high Al concentration (1.0 less th an or equal to x less than or equal to 1.5): for x less than or equal to 0.5 the compounds appear to have a complex magnetic structure, wher eas for the higher Al concentration a standard two-sublattice model yi elds values for the intra-and inter-sublattice coupling parameters. Fo r x less than or equal to 0.5, below the ordering temperature, the mag netic component of the electrical resistivity decreases with increasin g temperature, whereas for the higher Al concentration this component increases. These electrical properties are analysed in terms of a chan ge in the band gap with increasing Al concentration, taking into accou nt spin fluctuation terms. (C) 1998 Elsevier Science S.A.