CRITICAL MAGNETIC-SUSCEPTIBILITY OF GADOLINIUM

An extensive analysis of ac magnetic susceptibility measurements of si ngle-crystal gadolinium is presented. The demagnetization-corrected c- axis data are analyzed on the basis of a power law of the form chi(c)= At--gamma where t is the reduced temperature above T-c. Our results yi eld effective values of T-c=293.57 K and gamma=1.327. The basal plane susceptibility is expressed as a parametric equation in terms of the c -axis susceptibility chi(ab)(-1)=B'+C'chi(c)(-y/gamma). The exponent y , which is related to the critical exponent associated with the specif ic heat alpha as y=1-alpha, is determined by our analysis to be y=1.01 (2). This gives a temperature scale associated with the anisotropy as t(anis)=2.0x10(-3). These results are interpreted in the context of th e effects of dipolar interactions in the critical region.