Electron spin resonance of Gd1-xDyxAl2

The electron spin resonance spectra of Gd 1-x Dy x Al 2 have been observed for compounds with 0<or=x<0.2. The linewidths of the spectra may be interpreted in terms of a modified Hasegawa theory and provide evidence for the existence of large anisotropic exchange contributions at the Dy site. A negative g shift is found which is difficult to interpret on the basis of presently available theories. The lattice parameters and Curie temperatures of the compounds have been measured for 0